Q1. easy
A push or a pull on an object is called a:
- A Force
- B Speed
- C Distance
- D Temperature
Answer: A — Force
A force is a push or a pull acting on an object. Forces can move objects, stop them, or change their shape, size, direction or speed.
⚛️ Physics · Topic 7 of 10
Force & Pressure — Physics Questions with Answers
Start with the study notes on Force & Pressure (definitions, examples and a quick revision), then work through 60 practice questions, each with the correct answer and a clear explanation of why it is right. When you are ready, take this topic as an interactive quiz to test yourself.
Topic overview
Force and Pressure – pushes, pulls and how hard they press
1. What is a force?
A force is a push or a pull on an object.
Examples:
- Push: kicking a football, or closing a door.
- Pull: opening a drawer, or drawing water from a well.
Force is measured in newtons (N). One newton is roughly the force needed to hold up a 100-gram object.
Remember: A force has a size (magnitude) and a direction.
2. What can a force do?
- Start or stop motion: kicking a ball, or catching it.
- Change speed: pedalling harder makes a bicycle go faster.
- Change direction: a batter hitting a ball.
- Change shape: pressing dough, or squeezing a sponge.
3. Combining forces
- Same direction: forces add up. 8 N + 5 N = 13 N.
- Opposite directions: forces subtract, and the object moves towards the larger force. 12 N − 7 N = 5 N.
Balanced and unbalanced forces
- Balanced forces are equal and opposite. The net force is zero, so the motion does not change.
- Unbalanced forces leave a net force that is not zero, so they change the motion.
Example: In a tug-of-war where both teams pull equally, the rope does not move: the forces are balanced. When one team pulls harder, the rope moves towards them.
4. Contact and non-contact forces
Contact forces act only when the objects touch:
- Muscular force: from our muscles, as in lifting or pushing.
- Friction: between surfaces, opposing motion.
Non-contact forces act across a gap, without touching:
- Gravity: pulls everything towards the Earth and gives objects their weight. A ball thrown up comes back down.
- Magnetic force: a magnet pulls iron from a distance.
- Electrostatic force: a comb rubbed on dry hair picks up bits of paper.
5. Pressure
Pressure is the force acting on each unit of area.
Pressure = Force ÷ Area
The same force on a smaller area gives more pressure; on a larger area, it gives less pressure.
Using high pressure (small area)
Examples:
- Knives have sharp edges, so they cut easily.
- Nails, needles and pins have pointed tips, so they pierce easily.
Using low pressure (large area)
Examples:
- School bags have broad straps, so they don't dig into the shoulders.
- Camels have wide feet, so they don't sink into sand.
- Trucks have many wide tyres, and tall buildings have wide foundations.
- Skis spread a skier's weight, so the skier glides over the snow.
6. Pressure in liquids and gases
Liquids press on the bottom and sides of their container, in all directions. The pressure increases with depth.
Examples:
- Dams are built thicker at the bottom, where the water pressure is greatest.
- Water spurts farther from a hole near the bottom of a bottle than from a hole near the top.
Gases also press on the walls of their container, in all directions.
Example: The air inside keeps a tyre or a balloon firm.
7. Atmospheric pressure
Atmospheric pressure is the pressure of the air around the Earth, pressing on everything. It is measured with a barometer.
We are not crushed by it, because the fluids inside our bodies press outwards just as hard.
Examples:
- Sipping through a straw lowers the pressure inside it, and atmospheric pressure pushes the drink up.
- A rubber sucker sticks to a wall because the air outside presses it in place.
- Atmospheric pressure is lower high up on mountains, which is why sealed packets puff up there.
8. Common misconceptions
| Misconception | Correct understanding |
|---|---|
| A bigger force always means a bigger pressure. | Area matters too: the same force on a smaller area gives more pressure. |
| Forces of 12 N and 7 N always add up to 19 N. | Only if they act in the same direction. In opposite directions, they give 5 N. |
| Balanced forces means no forces are acting. | The forces are there; they just cancel each other out. |
| Water pressure depends on the shape or width of the container. | It depends on depth (and on the liquid), not on the shape. |
| Gravity needs contact. | Gravity is a non-contact force. |
9. Quick revision
- Force
- A push or a pull.
- Newton (N)
- The SI unit of force.
- Balanced forces
- Equal and opposite forces; the net force is zero.
- Contact force
- Needs touching, e.g. muscular force and friction.
- Non-contact force
- Acts across a gap, e.g. gravity and magnetism.
- Weight
- The pull of gravity on an object.
- Pressure
- Force ÷ area.
- Atmospheric pressure
- The pressure of the air around us.
10. Test your understanding
Give one example of a push and one of a pull.
Show answer
Push: closing a door. Pull: opening a drawer.
Forces of 12 N and 7 N act in opposite directions. What is the net force?
Show answer
5 N, in the direction of the 12 N force.
Why does the rope not move in an even tug-of-war?
Show answer
The forces are balanced, so the net force is zero.
Name three non-contact forces.
Show answer
Gravity, magnetic force and electrostatic force.
Why are knives sharp?
Show answer
A small edge area gives high pressure, so they cut easily.
Why do school bags have broad straps?
Show answer
A larger area reduces the pressure on the shoulders.
Why are dams thicker at the bottom?
Show answer
Water pressure increases with depth.
How does a drinking straw work?
Show answer
Sucking lowers the pressure inside it, and atmospheric pressure pushes the drink up.
Key takeaway: A force is a push or a pull; pressure is how concentrated that force is. Small area, big pressure; big area, small pressure.
Notes written by Velnov for Class 6–8 students, following the topics of the NCERT science syllabus.
Key concepts in this topic
Easy questions (2)
Q57. easy
Which of these is a push force?
- A Pushing a door to close it
- B Pulling a drawer open
- C Drawing water from a well
- D Lifting a bucket up
Answer: A — Pushing a door to close it
Pushing a door away from you is a push force. Pulling a drawer, drawing water, and lifting a bucket are pull forces. Both pushes and pulls are forces.
Medium questions (29)
Q2. medium
The SI unit of force is the:
- A Newton (N)
- B Metre
- C Kilogram
- D Joule
Answer: A — Newton (N)
Force is measured in newtons (N), named after Sir Isaac Newton. One newton is roughly the force needed to hold a 100-gram object against gravity.
Q3. medium
A force applied on an object can change the object's:
- A State of motion (speed/direction) or its shape
- B Colour
- C Temperature only
- D Smell
Answer: A — State of motion (speed/direction) or its shape
A force can start motion, stop motion, speed up or slow down an object, change its direction, or change its shape and size. These are the effects of a force.
Q6. medium
If two equal forces act on an object in opposite directions, the net force is:
- A Zero (the forces balance)
- B Double the force
- C Half the force
- D The larger force
Answer: A — Zero (the forces balance)
Two equal and opposite forces cancel out, giving a net (resultant) force of zero. Such balanced forces do not change the object's state of motion.
Q9. medium
A force that acts only when two objects are in contact is called a:
- A Contact force (e.g., muscular force, friction)
- B Non-contact force
- C Magnetic force
- D Gravitational force
Answer: A — Contact force (e.g., muscular force, friction)
Contact forces act when objects touch - examples are muscular force (from muscles) and friction (between surfaces). They require direct contact between the objects.
Q10. medium
A force that can act WITHOUT the objects touching is called a:
- A Non-contact force (e.g., gravity, magnetic force, electrostatic force)
- B Contact force
- C Muscular force
- D Frictional force
Answer: A — Non-contact force (e.g., gravity, magnetic force, electrostatic force)
Non-contact forces act at a distance without touching. Examples: gravitational force, magnetic force and electrostatic force. A magnet attracts iron from a distance without touching it.
Q12. medium
The force that opposes the motion of one surface over another is called:
- A Friction
- B Gravity
- C Magnetic force
- D Muscular force
Answer: A — Friction
Friction is the force that opposes motion between two surfaces in contact. It acts opposite to the direction of motion and always tends to slow moving objects down.
Q13. medium
The force that pulls all objects toward the Earth is called:
- A Gravitational force (gravity)
- B Magnetic force
- C Muscular force
- D Frictional force
Answer: A — Gravitational force (gravity)
Gravity is the force of attraction that pulls objects toward the Earth (and exists between all masses). It is why objects fall down and why we have weight. It is a non-contact force.
Q15. medium
The force between electrically charged objects (like a charged comb attracting bits of paper) is called:
- A Electrostatic force
- B Muscular force
- C Frictional force
- D Gravitational force
Answer: A — Electrostatic force
Electrostatic force acts between charged objects. A comb rubbed on dry hair becomes charged and attracts tiny bits of paper without touching them - a non-contact electrostatic force.
Q18. medium
Why are the edges of a knife and the tips of nails made SHARP (pointed)?
- A A small area gives more pressure, so they cut or pierce easily
- B A large area gives more pressure
- C They look nicer
- D To reduce the force needed to hold them
Answer: A — A small area gives more pressure, so they cut or pierce easily
A sharp edge or tip has a very small area. The same force applied over this tiny area creates high pressure, allowing the knife to cut and the nail to pierce with less effort.
Q19. medium
Why do the straps of heavy school bags/rucksacks have BROAD (wide) straps?
- A A larger area spreads the force, reducing pressure on the shoulder
- B Wide straps look better
- C They increase the pressure
- D They make the bag lighter
Answer: A — A larger area spreads the force, reducing pressure on the shoulder
Broad straps spread the load over a larger area of the shoulder. Since pressure = force / area, a larger area means less pressure, so the strap is more comfortable and does not dig into the shoulder.
Q21. medium
A camel and other animals walking on sand have WIDE feet so that they:
- A Exert less pressure on the sand and do not sink in
- B Run faster
- C Look bigger
- D Exert more pressure on the sand
Answer: A — Exert less pressure on the sand and do not sink in
Wide feet spread the animal's weight over a larger area, reducing the pressure on the soft sand. This helps camels walk on desert sand without sinking.
Q24. medium
Liquids exert pressure in:
- A All directions (sideways, downward and upward)
- B Only downward
- C Only sideways
- D Only upward
Answer: A — All directions (sideways, downward and upward)
A liquid exerts pressure equally in all directions at a given depth - on the bottom, the sides of the container, and even upward on objects placed in it. This is why water squirts out sideways from a hole in a container.
Q26. medium
The pressure exerted by the huge blanket of air surrounding the Earth is called:
- A Atmospheric pressure
- B Liquid pressure
- C Muscular pressure
- D Magnetic pressure
Answer: A — Atmospheric pressure
The atmosphere (air around the Earth) has weight and exerts atmospheric pressure on everything, in all directions. We do not feel crushed because the pressure inside our bodies balances it.
Q29. medium
When you suck a drink through a straw, the drink rises because:
- A You lower the pressure in the straw, and atmospheric pressure pushes the drink up
- B You pull the drink with a magnet
- C The drink is lighter than air
- D The straw heats the drink
Answer: A — You lower the pressure in the straw, and atmospheric pressure pushes the drink up
Sucking removes air from the straw, lowering the pressure inside it. The atmospheric pressure pushing down on the drink in the glass then forces the liquid up the straw and into your mouth.
Q31. medium
Which of these is a NON-CONTACT force?
- A Gravitational force
- B Muscular force
- C Frictional force
- D A push
Answer: A — Gravitational force
Gravitational force acts at a distance without contact (a non-contact force). Muscular force, friction and a push are contact forces, requiring the objects to touch.
Q33. medium
The strength of a force is described by its:
- A Magnitude (how big it is)
- B Colour
- C Smell
- D Temperature
Answer: A — Magnitude (how big it is)
A force has both magnitude (strength, measured in newtons) and direction. A larger magnitude means a stronger push or pull.
Q35. medium
In a tug-of-war, if both teams pull with equal force, the rope:
- A Does not move (the forces are balanced)
- B Moves toward the weaker team
- C Breaks
- D Flies up
Answer: A — Does not move (the forces are balanced)
Equal and opposite forces from the two teams are balanced, so the net force is zero and the rope does not move. If one team pulls harder, the unbalanced force moves the rope toward them.
Q37. medium
Which of the following is an example of a CONTACT force?
- A Kicking a football
- B The Earth pulling a falling apple
- C A magnet attracting a pin from a distance
- D A charged balloon attracting hair
Answer: A — Kicking a football
Kicking a ball requires the foot to touch the ball, so it is a contact (muscular) force. Gravity, magnetism and electrostatic attraction are non-contact forces that act at a distance.
Q39. medium
Two forces of 8 N and 5 N act on a box in the same direction. The net force is:
- A 13 N
- B 3 N
- C 40 N
- D 5 N
Answer: A — 13 N
Forces in the same direction add: 8 N + 5 N = 13 N in that direction.
Q41. medium
The force of gravity gives an object its:
- A Weight
- B Colour
- C Length
- D Speed
Answer: A — Weight
Weight is the force with which the Earth's gravity pulls an object down. That is why an object weighs less on the Moon (weaker gravity) than on Earth, even though its mass is the same.
Q43. medium
Which of these actions uses a PULL force?
- A Opening a drawer / drawing water from a well with a rope
- B Kicking a ball
- C Pressing a doorbell
- D Pushing a cart forward
Answer: A — Opening a drawer / drawing water from a well with a rope
Opening a drawer or pulling water up from a well are pull forces (toward you). Kicking, pressing and pushing a cart are push forces (away from you). Both pushes and pulls are forces.
Q45. medium
The instrument used to measure atmospheric pressure is a:
- A Barometer
- B Thermometer
- C Speedometer
- D Ammeter
Answer: A — Barometer
A barometer measures atmospheric pressure. Changes in atmospheric pressure help in weather forecasting - a falling barometer often signals a storm.
Q47. medium
Which of these correctly matches the force with its type?
- A Gravity - non-contact; friction - contact; magnetism - non-contact
- B Gravity - contact; friction - non-contact
- C Muscular force - non-contact; magnetism - contact
- D Friction - non-contact; gravity - contact
Answer: A — Gravity - non-contact; friction - contact; magnetism - non-contact
Gravity and magnetism are non-contact forces (act at a distance). Friction and muscular force are contact forces (need the objects to touch).
Q49. medium
Skis (long, flat boards worn on the feet) let a person move over snow without sinking because they:
- A Increase the area of contact and lower the pressure on the snow
- B Make the person heavier
- C Increase the pressure on the snow
- D Are made of metal
Answer: A — Increase the area of contact and lower the pressure on the snow
Skis spread a person's weight over a large area of snow. The reduced pressure stops them from sinking into the soft snow, letting them glide on top.
Q51. medium
Which statement about force is TRUE?
- A A force can be a push or a pull and can change an object's motion or shape
- B A force can only push, never pull
- C A force has no direction
- D A force cannot change shape
Answer: A — A force can be a push or a pull and can change an object's motion or shape
A force is a push or a pull with both magnitude and direction. It can start, stop, speed up, slow down or turn an object, and can also change its shape or size.
Q53. medium
The pressure exerted by an object depends on the force applied and the:
- A Area over which the force acts
- B Colour of the object
- C Temperature of the object
- D Weight of the person applying it only
Answer: A — Area over which the force acts
Pressure = Force / Area. So for a given force, the pressure depends on the area of contact. A smaller area gives higher pressure; a larger area gives lower pressure.
Q55. medium
Which of the following is the correct formula for pressure?
- A Pressure = Force ÷ Area
- B Pressure = Force × Area
- C Pressure = Area ÷ Force
- D Pressure = Force + Area
Answer: A — Pressure = Force ÷ Area
Pressure = Force ÷ Area. This shows that pressure increases when the force increases or when the area decreases.
Q58. medium
Gravity, magnetic force and electrostatic force are all examples of:
- A Non-contact forces
- B Contact forces
- C Muscular forces
- D Frictional forces
Answer: A — Non-contact forces
Gravity, magnetism and electrostatic force can all act without the objects touching, so they are non-contact forces. Muscular force and friction are contact forces.
Q60. medium
Why is the tip of a sewing needle made very sharp?
- A A small tip area gives high pressure, so it pierces cloth easily
- B A sharp tip gives low pressure
- C It looks nicer
- D To make the needle heavier
Answer: A — A small tip area gives high pressure, so it pierces cloth easily
The needle's sharp tip has a tiny area. The force applied over this small area produces very high pressure, allowing the needle to pierce cloth easily. This is the same idea as a sharp knife or nail.
Hard questions (29)
Q4. hard
When two forces act on an object in the SAME direction, the net force is:
- A The sum of the two forces
- B The difference of the two forces
- C Zero
- D Always zero
Answer: A — The sum of the two forces
Forces in the same direction add up. For example, if two people push a box in the same direction with 10 N each, the net force is 10 + 10 = 20 N.
Q5. hard
When two forces act on an object in OPPOSITE directions, the net force is:
- A The difference of the two forces (in the direction of the larger)
- B The sum of the two forces
- C Always zero
- D Always the larger force
Answer: A — The difference of the two forces (in the direction of the larger)
Opposing forces subtract. If one force is 15 N and the other is 10 N in the opposite direction, the net force is 15 - 10 = 5 N, acting in the direction of the larger force.
Q7. hard
Forces that cancel each other out and do not change an object's motion are called:
- A Balanced forces
- B Unbalanced forces
- C Muscular forces
- D Magnetic forces
Answer: A — Balanced forces
Balanced forces are equal and opposite, producing zero net force. An object under balanced forces stays at rest or keeps moving as before (no change in motion), though its shape may change.
Q8. hard
Forces that do NOT cancel out and cause a change in an object's motion are called:
- A Unbalanced forces
- B Balanced forces
- C Equal forces
- D Zero forces
Answer: A — Unbalanced forces
Unbalanced forces have a non-zero net force, so they can start, stop, speed up, slow down or turn an object. A moving or stopping object is under unbalanced forces.
Q11. hard
The force exerted by our muscles to lift, push or pull objects is a:
- A Muscular force (a contact force)
- B Magnetic force
- C Gravitational force
- D Non-contact force
Answer: A — Muscular force (a contact force)
Muscular force is applied by the action of muscles in the body of humans and animals. It is a contact force, used to lift, push, pull, walk, and do many daily activities.
Q14. hard
When a ball is thrown up, it comes back down because of:
- A The gravitational force of the Earth
- B Friction with the air only
- C A magnetic force
- D A muscular force
Answer: A — The gravitational force of the Earth
The Earth's gravity constantly pulls the ball downward, slowing its rise, stopping it at the top, and then pulling it back down to the ground.
Q16. hard
The force exerted per unit area on a surface is called:
- A Pressure
- B Friction
- C Gravity
- D Speed
Answer: A — Pressure
Pressure = Force / Area. It is the force acting on each unit of area of a surface. The same force spread over a smaller area gives greater pressure.
Q17. hard
For the SAME force, pressure is GREATER when the area is:
- A Smaller
- B Larger
- C The same
- D Zero only
Answer: A — Smaller
Since pressure = force / area, a smaller area gives a larger pressure for the same force. This is why a sharp (small-area) knife or nail exerts high pressure and cuts or pierces easily.
Q20. hard
Why is the foundation (base) of a tall building made WIDE?
- A A larger base area reduces the pressure on the ground, keeping the building stable
- B To use more cement
- C To increase pressure on the ground
- D For decoration
Answer: A — A larger base area reduces the pressure on the ground, keeping the building stable
A wide foundation spreads the building's enormous weight over a large area of ground, reducing the pressure so the ground does not give way. This keeps tall buildings stable.
Q22. hard
Liquids exert pressure on the walls and bottom of their container. This pressure INCREASES with:
- A Depth (the deeper you go, the greater the pressure)
- B The colour of the liquid
- C The shape of the container only
- D Height above the liquid
Answer: A — Depth (the deeper you go, the greater the pressure)
Liquid pressure increases with depth because of the weight of the liquid above. That is why a dam is built thicker at the bottom, where the water pressure is greatest.
Q23. hard
Why are dams built THICKER at the bottom than at the top?
- A Water pressure is greatest at the bottom (it increases with depth)
- B To use less material
- C Water pressure is greatest at the top
- D For a nicer shape
Answer: A — Water pressure is greatest at the bottom (it increases with depth)
Because liquid pressure increases with depth, the water pushes hardest against the lower part of the dam. So the dam is made thicker and stronger at the bottom to withstand this greater pressure.
Q25. hard
Gases also exert pressure on the walls of their container. This is why a balloon or a tyre:
- A Inflates and stays firm when filled with air
- B Becomes heavier than lead
- C Becomes magnetic
- D Cools down
Answer: A — Inflates and stays firm when filled with air
The air (gas) inside a balloon or tyre pushes outward equally on all the walls, keeping it inflated and firm. Gases exert pressure in all directions, like liquids.
Q27. hard
We are not crushed by the large atmospheric pressure because:
- A The pressure of the fluids inside our body balances the outside atmospheric pressure
- B The atmosphere has no weight
- C We are too strong
- D Air does not press on us
Answer: A — The pressure of the fluids inside our body balances the outside atmospheric pressure
Atmospheric pressure pushes on us from outside, but the pressure of blood and other fluids inside our body pushes outward with equal force. These balance, so we do not feel or get crushed by the atmosphere.
Q28. hard
A rubber sucker sticks to a smooth surface because:
- A Air is pushed out, and the higher atmospheric pressure outside holds it in place
- B It is glued
- C It is magnetic
- D It is heated
Answer: A — Air is pushed out, and the higher atmospheric pressure outside holds it in place
Pressing a sucker pushes out the air beneath it, creating low pressure inside. The greater atmospheric pressure outside then pushes the sucker firmly against the surface, holding it in place.
Q30. hard
A wide wooden board is placed under a person lying on soft mud, so that they do not sink. This works because the board:
- A Spreads the weight over a larger area, reducing the pressure on the mud
- B Makes the person lighter
- C Increases the pressure on the mud
- D Is magnetic
Answer: A — Spreads the weight over a larger area, reducing the pressure on the mud
The board increases the area of contact with the mud. Since pressure = force / area, spreading the same weight over a larger area lowers the pressure, so the person does not sink into the soft mud.
Q32. hard
A force can change the SHAPE of an object. Which example shows this?
- A Pressing a lump of dough or squeezing a sponge
- B A ball rolling on the floor
- C A car speeding up
- D A stone falling down
Answer: A — Pressing a lump of dough or squeezing a sponge
Pressing dough or squeezing a sponge changes its shape - a force altering the shape of an object. The other examples show forces changing motion, not shape.
Q34. hard
A force acting on an object has both magnitude AND:
- A Direction
- B Colour
- C Weight only
- D Temperature
Answer: A — Direction
A force is described by both how strong it is (magnitude) and which way it acts (direction). Two forces of the same size in different directions can have very different effects.
Q36. hard
Which correctly describes the pressure a nail exerts when hammered into wood?
- A The pointed tip has a tiny area, giving very high pressure that pierces the wood
- B The wide head gives high pressure
- C Pressure has no role
- D The nail exerts low pressure
Answer: A — The pointed tip has a tiny area, giving very high pressure that pierces the wood
The nail's sharp point has a very small area. The hammer's force concentrated on this tiny area produces enormous pressure, which drives the nail into the wood. The wide head lets the hammer hit it safely.
Q38. hard
A porter carrying luggage on the head places a round cloth pad on the head to:
- A Increase the area of contact and reduce the pressure of the load
- B Make the load heavier
- C Increase the pressure
- D Keep the head warm
Answer: A — Increase the area of contact and reduce the pressure of the load
The pad increases the area over which the load presses on the head. Since pressure = force / area, a larger area lowers the pressure, making the heavy load more comfortable to carry.
Q40. hard
Two forces of 12 N and 7 N act on a box in OPPOSITE directions. The net force is:
- A 5 N (in the direction of the 12 N force)
- B 19 N
- C 84 N
- D 0 N
Answer: A — 5 N (in the direction of the 12 N force)
Opposing forces subtract: 12 N - 7 N = 5 N, and the net force acts in the direction of the larger (12 N) force.
Q42. hard
Why does a sharp pin pierce a cloth easily but a blunt one does not, even with the same force?
- A The sharp pin has a smaller tip area, so it produces greater pressure
- B The sharp pin is heavier
- C The blunt pin is magnetic
- D Force has no effect
Answer: A — The sharp pin has a smaller tip area, so it produces greater pressure
The sharp pin concentrates the force on a very small area, giving high pressure that pierces the cloth. A blunt pin spreads the same force over a larger area, giving lower pressure that cannot pierce as easily.
Q44. hard
A gas fills its container completely and exerts pressure on all its walls. This shows that gases:
- A Exert pressure in all directions
- B Exert pressure only downward
- C Do not exert any pressure
- D Only press upward
Answer: A — Exert pressure in all directions
Like liquids, gases exert pressure in all directions on the walls of their container. This is why a fully inflated ball or tyre feels firm all over.
Q46. hard
At higher altitudes (like on a tall mountain), atmospheric pressure is:
- A Lower than at sea level
- B Higher than at sea level
- C The same everywhere
- D Zero
Answer: A — Lower than at sea level
As you go higher, there is less air above you, so atmospheric pressure decreases. This is why mountaineers may find it hard to breathe, and why sealed packets puff up at high altitudes.
Q48. hard
A heavy truck has MANY wheels (and wide tyres). This is designed to:
- A Spread the weight over a larger area, reducing pressure on the road
- B Increase the pressure on the road
- C Make the truck lighter
- D Make the truck faster
Answer: A — Spread the weight over a larger area, reducing pressure on the road
More and wider wheels increase the total contact area with the road. This spreads the truck's heavy weight over a larger area, reducing the pressure and preventing damage to the road (and helping the tyres last).
Q50. hard
A liquid in a container with a small hole near the BOTTOM squirts out faster and farther than from a hole near the TOP because:
- A Pressure is greater at greater depth
- B The liquid is thinner at the bottom
- C The bottom hole is bigger
- D Gravity pushes only the top
Answer: A — Pressure is greater at greater depth
Liquid pressure increases with depth, so the water at the bottom hole is under greater pressure and rushes out with more force, travelling farther. Water from a higher hole (lower pressure) comes out more gently.
Q52. hard
A balloon filled with air bursts when pressed too hard because:
- A The pressure inside becomes too great for the rubber to hold
- B The air becomes magnetic
- C The balloon freezes
- D The air becomes heavier
Answer: A — The pressure inside becomes too great for the rubber to hold
Squeezing the balloon reduces its volume, increasing the pressure of the air inside. When this internal pressure exceeds what the rubber can withstand, the balloon bursts.
Q54. hard
Which everyday example shows the use of HIGH pressure (small area)?
- A A sharp knife cutting vegetables
- B A broad school-bag strap
- C A wide truck tyre
- D A camel's flat feet
Answer: A — A sharp knife cutting vegetables
A sharp knife has a very small edge area, giving high pressure to cut easily. The other examples all use large areas to REDUCE pressure. Sharp tools use high pressure; load-bearing designs use low pressure.
Q56. hard
Which overall statement about forces and pressure is CORRECT?
- A Forces change motion or shape; pressure is force per unit area, and both are central to everyday life
- B Force and pressure are the same thing
- C Pressure does not depend on area
- D Forces cannot change an object's shape
Answer: A — Forces change motion or shape; pressure is force per unit area, and both are central to everyday life
Forces (pushes and pulls) change the motion, direction or shape of objects. Pressure is the force acting per unit area. Understanding both explains cutting tools, dams, buildings, walking on sand, drinking straws and much more.
Q59. hard
The pressure at a point inside a liquid depends on:
- A The depth of the point below the surface
- B The colour of the liquid
- C The shape of the container only
- D The width of the container only
Answer: A — The depth of the point below the surface
Liquid pressure increases with depth (and depends on the liquid's density). It does not depend on the shape or width of the container - only on how deep below the surface the point is.