P10 Force and Motion

P10 Force and Motion

1. What is the name of the force caused by gravity acting on an object?

a) down-thrust
b) mass
c) drag
d) weight

2. Which of the following is a measure of the strength of gravity?

a) gravitational potential energy
b) gravitational field strength
c) weight
d) mass

3. The weight of an object depends on….

a) the gravitational field strength and its mass.
b) only its mass.
c) only the gravitational field strength.
d) its density and its weight.

4. Which of the following equations correctly links weight (W), gravitational field strength (g) and mass (m)?

a) W = mg
b) W = m/g
c) W = g/m
d) W = 1/mg

5. What is the standard unit of weight?

a) Nm
b) N
c) kg
d) J

6. What is the standard unit of mass?

a) kg
b) g
c) mg
d) m

7. Calculate the weight of a 2 kg dog in a gravitational field of 10 N/kg

a) 2 N
b) 5 N
c) 0.2 N
d) 20 N

8. Calculate the mass of a 15 N cat which is in a gravitational field of 10 N/kg

a) 150 kg
b) 1.5 kg
c) 1.5 g
d) 0.75 kg

9. Which of the following is the best definition of “centre of mass”

a) The point where the weight of an object cancels out with its mass.
b) The central point of any object with a weight.
c) The point at which an object will balance.
d) The single point at which the weight of an object can be considered to act.

10. Which of the following is true of the relationship between weight and mass?

a) They are independent of each other.
b) They are directly proportional.
c) They are inversely proportional.
d) They multiply together to give a constant.

11. Which of the symbols in the picture is used to represent proportionality in mathematical equations?

a) A
b) B
c) C
d) D

12. What is the name of a calibrated spring-balance used to measure weight?

a) weight meter
b) newtonmeter
c) scales
d) force meter

13. Why are two forces needed to stretch or squash a stationary object?

a) One force is never enough. The first sets up action of the second.
b) For the object to remain stationary the two forces must be equal and opposite giving no resultant force.
c) A single force will just cancel out with its interaction pair so there will be no resultant.
d) Forces always come in pairs so if you only have one you will break the laws of physics.

14. Which of these is an example of “elastic deformation”?

a) Heating an elastic material until it softens and deforms.
b) Pulling an elastic band until it snaps.
c) Squashing a cube of cheese
d) Stretching a spring a little bit so that it can return to its original length.

15. Which of these is an example of “inelastic deformation”?

a) Stretching a spring a little bit so that it can return to its original length.
b) Squashing a cube of cheese.
c) Pulling an elastic band until it snaps.
d) Heating an elastic material until it softens and deforms.

16. Which of the following is the correct equation that links force (F), spring constant (k) and extension (e)?

a) F = k / e
b) F = ke
c) k = Fe
d) k = e / F

17. In the equation above e represents extension but what else can it also represent in the equation?

a) energy
b) compression
c) electrons
d) elasticity

18. What type of energy is stored in a compressed or extended spring?

a) gravitational potential energy
b) mechanical potential energy
c) compressional energy
d) elastic potential energy

19. When a force stretches or compresses a spring what is said to be done?

a) energy storage
b) energy release
c) work
d) energy conversion

20. Which of the following is the best description of work?

a) The energy stored in a spring as it is compressed or extended.
b) The potential for energy transfer in a spring or elastic.
c) The number of J converted to Nm by a spring.
d) The energy transferred when a force moves a certain distance.

21. Calculate the force needed to extend a piece of elastic of spring constant 2 N/m by 0.5 m

a) 1 J
b) 2 J
c) 4 J
d) 8 J

22. Calculate the extension produced when a force of 0.5 N extends a spring of spring constant 2 N/m

a) 0.5 m
b) 1.0 m
c) 2.0 m
d) 0.25 m

23. A spring was compressed from 30cm to 20cm by a force of 200 N. Calculate the value of the spring constant in N/cm

a) 20 N/cm
b) 2 N/cm
c) 200 N/cm
d) 2000 N/cm

24. What additional force is needed to extend the spring from 5 cm to 15 cm?

a) 2 N
b) 4 N
c) 6 N
d) 8 N

25. At what extension does the spring exceed its elastic limit?

a) 15 cm
b) 10 cm
c) 20 cm
d) 30 cm

26. At what weight does the behaviour of the spring become non-linear?

a) 2 N
b) 4 N
c) 6 N
d) 8 N

27. What is the spring constant of the spring before it reaches its elastic limit?

a) 2.5 N/cm
b) 15 N/cm
c) 0.3 N/cm
d) 0.4 N/cm

28. All three springs shown on the graph show the same relationship. What is that relationship?

a) inversely proportional
b) non-linear
c) directly proportional
d) independent of each other

29. Which spring has the highest spring constant?

a) L
b) K
c) M

30. Which spring has a spring constant of 1 N/cm

a) L
b) M
c) K

31. Calculate the spring constant of spring K

a) 3.4 N/cm
b) 0.29 N/cm
c) 34 N/cm
d) 10 N/cm

32. Which of the following is the best description of Newton’s First Law.

a) One force leads to another.
b) A force is needed to keep an object in motion.
c) The sum of all the forces on an object is always zero.
d) A force is needed to change the motion (accelerate) an object.

33. Which of the following statements is not true?

a) Objects keep moving when there is no resultant force on them.
b) Forces always come in a pair of equal and opposite forces each acting on a different object.
c) A moving object must have a resultant force on it.
d) Forces are vectors so have magnitude and direction.

34. When a car is travelling at constant velocity then …..

a) the driving force is greater than the resistive forces.
b) the driving force is less than the resistive forces.
c) the driving force and resistive forces add up to zero.
d) the driving force and resistive forces add up to more than its weight.

35. What term is used to mean the tendency of objects to continue in their state of rest or of uniform motion?

a) momentum
b) impetus
c) motivation
d) inertia

36. Which of the following is the best description of Newton’s Second Law? When a force acts on an object with mass the acceleration is…

a) proportional to the mass and inversely proportional to the force.
b) proportional to the force and mass.
c) inversely proportional to the force and mass.
d) proportional to force and inversely proportional to mass.

37. Which of the following equations represents Newton’s Second Law?

a) F = ma
b) F = m/a
c) F = a/m
d) a = m / F

38. The mass in the equation above measures how hard it is to change the velocity of an object. What name is given to this measure?

a) resultant mass
b) gravitational mass
c) inertial mass
d) total mass

39. Which of the following equations defines the mass in Newton’s Second Law?

a) m = Fa
b) m = a / F
c) m = F /a
d) m = aF

40. A force of 12 N acts on a mass of 3 kg. Calculate the acceleration.

a) 4 m/s²
b) 36 m/s²
c) 0.25 m/s²
d) 9 m/s²

41. A mass of 4 kg accelerates at 3 m/s². Calculate the force producing the acceleration.

a) 0.75 N
b) 1.3 N
c) 7 N
d) 12 N

42. A force of 15 N causes a mass to accelerate at 5 m/s². Calculate the size of the mass.

a) 0.33 kg
b) 3 kg
c) 20 kg
d) 25 kg

43. Which of the following symbols is used to indicate that a value is approximate?

a) A
b) B
c) C
d) D

44. Which of the symbols is used to indicate that a value represents a change in a quantity?

a) A
b) B
c) C
d) D

45. What are the two components of the stopping distance of a vehicle?

a) thinking distance and braking distance
b) reaction time and braking distance
c) braking power and reaction time
d) stopping power and thinking time

46. Which of the following is the best description of thinking distance?

a) The time the driver takes to react.
b) The distance the car travels during the time it takes for the brakes to work.
c) The distance the vehicle travels during the driver’s reaction time.
d) The time it takes for the vehicle’s braking system to work.

47. Which of the following is the best description of braking distance?

a) The time it takes for the brakes to work.
b) The distance a vehicle travels up to when the braking force begins.
c) The distance a vehicle travels once the braking force begins.
d) The distance the vehicle travels during the driver’s reaction time.

48. Assuming the braking force stays the same, what happens to the stopping distance as the speed of the vehicle increases.

a) It decreases
b) It increases
c) It also stays the same
d) It is not possible to predict

49. Assuming the braking force stays the same, what happens to the thinking distance as the speed of the vehicle increases.

a) It decreases
b) It increases
c) It also stays the same
d) It is not possible to predict

50. Assuming the braking force stays the same, what happens to the braking distance as the speed of the vehicle increases.

a) It decreases
b) It increases
c) It also stays the same
d) It is not possible to predict

51. The graph shows the motion of a vehicle. The drives see an obstacle in the road at time t = 0 and reacts and brakes to a stop. At what speed was the vehicle travelling?

a) 35 mph
b) 35 km/h
c) 35 km/s
d) 35 m/s

52. What was the reaction time of the driver?

a) 4.6 s
b) 0.0 s
c) 0.6 s
d) 1.0 s

53. Which calculation gives the thinking distance?

a) 35 / 0.6 = 58 m
b) 35 x 4.6 = 161 m
c) 35/2 x 0.6 = 10.5 m
d) 35 x 0.6 = 21 m

54. Which calculation gives the braking distance?

a) 35 x 2 / 2 = 35 m
b) 35 x 4 / 2 = 70 m
c) 35 x 4 = 140 m
d) 35 x 4 x 2 = 280 m

55. Which calculation gives the stopping distance?

a) 58 + 35 = 93 m
b) 70 - 21 = 49 m
c) 70 + 58 = 128 m
d) 21 + 70 = 91 m

56. Which of the following gives a typical range of human reaction times?

a) 1.2s to 1.9 s
b) 2.2 s to 2.9 s
c) 0.02 s to 0.09 s
d) 0.2 s to 0.9 s

57. Which of these things that commonly affect reaction time?

a) tiredness
b) drugs
c) alcohol
d) distractions and the other three

58. Which of the following can affect braking distance?

a) poor road surface
b) wet or icy weather conditions
c) worn brakes or tyres
d) all three of the above

59. When the brakes are applied which force in the brakes slows the vehicle?

a) drag
b) resistance
c) counter
d) friction

60. Which of the following gives the energy transfer that happens in the brakes?

a) kinetic to thermal
b) kinetic to potential
c) kinetic to elastic
d) kinetic to chemical

61. What happens to the temperature of brakes when they are in use?

a) It decreases
b) It is constant
c) It increases
d) It is not possible to predict

62. If the braking force is increased what happens to the stopping distance?

a) It increases
b) It decreases
c) It stays the same
d) It is not possible to predict

63. What is the link between braking force and deceleration?

a) The larger the braking force the greater the deceleration.
b) The larger the braking force the lower the deceleration.
c) Braking force and deceleration are independent of each other.
d) Breaking force and deceleration multiply together to give a constant.

64. Large decelerations may lead to ……

a) brakes overheating.
b) all the other three.
c) loss of control.
d) large forces that may cause injury.

65. Which of these equations correctly defines momentum?

a) momentum = mass / velocity
b) momentum = velocity / mass
c) momentum = mass x velocity
d) momentum = mass x velocity²

66. What phase is used to mean that the total momentum before a collision is always the same as the total momentum after the collision?

a) First Law of Momentum
b) Conservation of Momentum
c) Equality of Momentum
d) Momentum equals momentum.

67. Which of the following is the standard unit of momentum?

a) kg m/s
b) N/s
c) Nm/s
d) N/kg

68. A 10 kg trolley travelling at 6 m/s collides and sticks to another stationary 10 kg trolley. Calculate the velocity of the pair of trolleys after the collision.

a) 1.5 m/s
b) -3 m/s
c) 12 m/s
d) 3 m/s

69. A 10 kg trolley travelling at 5 m/s collides and sticks to a stationary 40 kg trolley. Calculate the velocity of the pair of trolleys after the collision.

a) 6 m/s
b) 0.2 m/s
c) 1 m/s
d) 20 m/s

70. A 10 kg trolley travelling at 10 m/s collides and sticks to a 20 kg trolley travelling at -5 m/s. Calculate the velocity of the pair of trolleys after the collision.

a) 0 m/s
b) 15 m/s
c) -5 m/s
d) 5 m/s

71. Combining F=ma and a = ∆v/∆t gives…..

a) F = ∆v/m∆t
b) F = mt/∆v
c) F = ∆t/m∆v
d) F = m∆v/∆t

72. The equation F = m∆v/∆t translates to:

a) The bigger the mass the bigger the force
b) Bigger forces last for longer
c) Force equals the rate of change of momentum
d) Increasing the time a force acts for, reduces the mass

73. Use the equation F = m∆v/∆t to calculate the force needed to accelerate a 10 kg trolley from 0m/s to 5 m/s in 2s

a) 25 N
b) 50 N
c) 5 N
d) 15 N

74. Use the rearranged equation ∆t = m∆v/F to calculate the time of an impact with average force 5000 N where a 10 kg rock travelling at 5 m/s hits the ground and stops.

a) 0.01 s
b) 0.5 s
c) 0.1 s
d) 0.05 s

75. The equation F = m∆v/∆t shows that if the time ∆t of an impact is doubled then the force of the impact will…

a) decrease
b) half
c) double
d) not change

76. Seat belts, air bags and crash mats and cycle helmets all work by… (choose the best explanation)

a) increasing the time of an impact so the forces involved are reduced.
b) acting as a cushion.
c) absorbing the momentum so less is available to cause injury.
d) making the impact shorter so less damage is done.

This is more feedback!

This is the feedback!

feedback!