Linear & Projectile Motion (OCR AS Physics)

Topic Questions

1a3 marks
a)
A car is travelling along a straight road at 18 ms–1.
The driver sees an obstacle and after 0.50 s applies the brakes.
The stopping distance of the car is 38 m.

Calculate the magnitude of the deceleration of the car when the brakes are applied.

deceleration = ................................ ms–2      [3]

1b6 marks
b)
A student rolls a marble at different speeds on a carpet to model the braking of a car.

The student wishes to investigate how the total distance x travelled before the marble stops (braking distance) depends on its initial speed v.
The speed v and distance x are related by the equation 1 halfmv 2 = Fx where m is the mass of the marble and F is the constant frictional force acting on the marble.

  • Describe how an experiment can be conducted in the laboratory to investigate the relationship between v and x.
  • Explain how the data can be analysed to determine F.

[6]

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2a6 marks
a)
A tennis ball is struck with a racket.
 
The initial velocity v of the ball leaving the racket is 30.0 m s−1 and it makes an angle of 70° to the horizontal as shown in Fig. 16.
 
Air resistance is negligible

q16a-paper-1-june-2018-ocr-a-level-physics

i)
Calculate the vertical component of the initial velocity of the ball.
 


vertical component = .................................................m s−1 [1]

ii)
Use your answer in (i) to show that the ball reaches a maximum height h of about 40 m.
 


h
= ...................................................... m [2]

iii)
Explain why the kinetic energy of the ball is not zero at maximum height.

 [1]

iv)
The mass m of the ball is 57.0 g.
 
Calculate the kinetic energy Ek of the ball when it is at its maximum height.

 

Ek = ....................................................... J [2]

2b6 marks
b)
A metal ball is rolled off the edge of a horizontal laboratory bench. The initial horizontal velocity of the ball is v. The ball travels a horizontal distance x before it hits the level floor.
 
Use your knowledge of projectile motion to suggest the relationship between v and x. Describe how an experiment can be safely conducted to test this relationship and how the data can be analysed.
[6]

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1a2 marks

An archer fires an arrow towards a target as shown below.

q18-paper-1-nov-2020-ocr-a-level-physics

The diagram is not drawn to scale.

The centre of the target is at the same height as the initial position of the arrow.
The target is a distance of 90 m from the arrow.
The arrow has an initial velocity of 68 ms–1 and is fired at an angle of 11° to the horizontal.

Air resistance has negligible effect on the motion of the arrow.

a)
Describe how the kinetic energy of the arrow changes during its journey from when it is fired until it reaches its maximum height.

[2]

1b2 marks
b)
Show that the time taken for the arrow to reach its maximum height is about 1.3 s.

[2]

1c3 marks
c)
The arrow misses the target.

Calculate the horizontal distance, measured along the base line, by which the arrow misses the target.





horizontal distance = ......................................... m [3]

1d3 marks
d)
The arrow is now fired horizontally at 68 m s–1 into the target at very close range.

q18d-paper-1-nov-2020-ocr-a-level-physics

The arrow sticks into the target. The collision between the arrow and the target is inelastic.

i)
Explain what is meant by an inelastic collision.

[1]

ii)
The target is mounted on wheels. The target has a much larger mass than the mass of the arrow.

Using ideas of momentum, explain the velocity of the target immediately after the arrow sticks into the target.

[2]

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