Questions Q1



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Q1.

The diagram shows the forces acting on a car which is travelling along a flat straight road.



     Forces also act on objects when they fall through the air.

     There are two forces acting on this ball as it falls through the air.

     The weight is shown on the diagram.



(i) Draw and label an arrow on the diagram to show the other force acting on the ball.



(2)

(ii) Use words from the box to complete the sentences.



(2)

     balanced      changing      greater      smaller      zero     

After a short time the ball falls at a steady speed.

The forces acting on the ball are now . . . . . . . . . . . . . . . . . . . . . . .

The acceleration of the ball is now . . . . . . . . . . . . . . . . . . . . . . .

Q2.
Forces and motion

The graph shows a velocity-time graph for a cyclist over a time of 60 s.



(a) (i)   When is the cyclist travelling with greatest velocity?

Put a cross () in the box next to your answer.

(1)

    A  for the first 15 seconds

    B  between 15 and 40 seconds

    C  between 40 and 50 seconds

    D  for the last 10 seconds

(ii)  Calculate how long the cyclist is stationary for.



(1)

answer = .................................... seconds

(b) The cyclist in this picture is travelling at a constant velocity.

Her muscles produce a driving force of 15 N.



Draw an arrow on the diagram to show the size and direction of the overall resistive force acting on the cyclist.



(1)

(c) The cyclist accelerates at 1.4 m/s2.

The mass of the cyclist and bicycle is 60 kg.

(i)   Calculate the resultant force.



(2)

resultant force = ....................................... N

(ii)  The cyclist accelerates for 8 s.

Calculate the increase in velocity during this time.



(3)

increase in velocity = ............................... m/s



Q3.

The graph shows how the velocity of a small car changes with time.



(a) Complete the sentence by putting a cross ( ) in the box next to your answer.

 The resultant force on the car will be zero when the car is

(1)

   A   accelerating

   B   decelerating

   C   changing velocity

   D   moving at a constant velocity

(b) (i) Use the graph to estimate the velocity of the car at three seconds.



(1)

      ..............................................................................................................................................

(ii) Calculate the acceleration of the car when it is speeding up.

(2)

 

 



 

 

acceleration = . . . . . . . . . . . . . . . . . . . . . . m/s2



(iii) Explain why the units of acceleration are m/s2.

(2)

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(iv) Show that the car travels further at a constant velocity than it does when it is slowing down.



(3)

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(Total for Question is 9 marks)

Q4.

(a) A car is travelling along a level road.



(i) Complete the sentence by putting a cross ( ) in the box next to your answer.

When the velocity of the car is constant, the force of friction on it is

(1)

   A   zero

   B   greater than the driving force

   C   smaller than the driving force

   D   the same size as the driving force

(ii) The car now accelerates in a straight line.


     Its average acceleration is 12 m/s2.

Calculate the increase in velocity of the car in 4.0 s.



(3)

 

 



 

 

      ..............................................................................................................................................



(b) This table shows data about two other cars.

The owner of the family car claims that although the sports car has greater acceleration, it produces a smaller accelerating force than his family car.

Explain how these figures support his claim.

(2)

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

*(c) After going to the shops, a car driver places a bag of shopping on the passenger seat. During the journey home, the driver        has to use the brakes to stop very suddenly. The driver is wearing a seat belt.

   Explain what happens next to the car, the driver and the shopping bag.



(6)

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(Total for Question = 12 marks)

(c)

This six-mark question presented candidates with the opportunity to show their power of written communication in a familiar situation. There were quite a few examples of candidates presenting pre-prepared but irrelevant answers about breaking (sic) distances etc and the use of air bags and crumple zones.

The vast majority were able to compare the relative decelerations of the driver, car and shopping, although this was little more than common observation from an every day situation. Since this was a science examination, various degrees of explanation were needed to progress to higher levels. As the question was open-ended, there was opportunity to explain what happened in terms of forces and/or energy and/or momentum.



Results Plus: Examiner Comments

For this, there is limited comparison of the decelerations of the person and the shopping. There is little more here than common observation. It is a level 1 answer for 2 marks. To move to level 2, some science needs to be used to explain at least one of the decelerations.




Results Plus: Examiner Comments

There is a clear comparison of the decelerations of all three objects. Combined with the effect of the seat belt on the rate of change of momentum, and the explanation of the effect of rapid change in momentum on the shopping, shows sufficient science to move this into a level 2 answer worth 4 marks. A little more science, for example in terms of stretching of the seat belt or further explanation of the shopping continuing at the same velocity, would have raised this to a level 3 response.




Results Plus: Examiner Comments

There is insufficient relevant science or everyday observation of the effect to score any marks. Technical terms such as kinetic energy, momentum and conserved are used but convey little scientific understanding. This scores 0 marks.




Results Plus: Examiner Comments

There is good comparison of the relative decelerations of all three objects and some science implied during discussion of the idea of inertia or conservation of momentum for the shopping bag. Misspellings of brakes and immediately are not serious enough to reduce the mark for quality of written communication. This is a level 2 answer scoring 4 marks despite the erroneous statement about the driver being forced forward.



Mark Scheme

Q1.




 

Answer

Acceptable answers

Mark

(i)

    (1) air resistance
(1)

upward arrow on any part of line vertical line from any point on the diagram air friction, upthrust, drag Ignore any downward arrow labelled weight or gravity  

(2)

(ii)

Balanced (1) Zero (1)

 

(2)

 

Q2.



Question
Number

Answer

Acceptable answers

Mark

(a)(i)

B

 

(1)

Question
Number

Answer

Acceptable answers

Mark

(a)(ii)

10 (s)

 

(1)

Question
Number

Answer

Acceptable answers

Mark

(b)

horizontal arrow, same length as driving force, pointing to the left

horizontal arrow, labelled 15 N, pointing to the left

(1)

Question
Number

Answer

Acceptable answers

Mark

(c)(i)

substitution (1) 60 × 1.4 evaluation (1) = 84 (N)

give full marks for correct answer, no working

(2)

Question
Number

Answer

Acceptable answers

Mark

(c)(ii)

Substitution (1) 1.4 = velocity change/ 8 transposition (1) velocity change = 1.4 x 8 evaluation (1) = 11.2 (m/s)

allow substitution and transposition in either order give full marks for correct answer, no working

(3)


Q3.



 

Answer

Acceptable answers

Mark

(a)

D

 

(1)

(b)(i)

12 (m/s)
(1)

Range from 11(m/s) to 14
(m/s)

(1)

(b)(ii)

Substitution      (1)
20-0
   5 evaluation        (1)
4 (m/s2)

20
 5 Full marks for correct answer with no working Allow answers between 3.6 and 4.7 for 2 marks to reflect readings taken from the graph

(2) 

b(iii)

· velocity/ speed (measured in) m/s   (1)

· divided by time in s (1)


velocity/ speed (measured in) ms-1 acceleration is rate of change of velocity m/s/s m per s per s
[accept per for divide] do not accept     m/s times time  

(2)

b(iv)

at constant vel
· distance = 60 (m) (1) slowing down
· distance = ½×2×20 (1)
· = 20 (m) (1)  

      correct answer scores 2 marks

(3)

Total for question = 10 marks

 

Q4.



 





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