Forces and motion part 1 practise questions and answers	

	Name:	
________________________	

Class:	
________________________	

Date:	
________________________	

 	
Time:	50 minutes	
Marks:	50 marks	
Your score:

What went well:

How to improve:

		

Q1.
A student carried out an investigation to determine the spring constant of a spring.
The table below gives the data obtained by the student.
 
Force in N	Extension in cm	
0	0.0	
2	3.5	
4	8.0	
6	12.5	
8	16.0	
10	20.0	
(a)  Describe a method the student could have used to obtain the data given in the table above.
Your answer should include any cause of inaccuracy in the data.
Your answer may include a labelled diagram.
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 (6)
(b)  The student measured the extension for five different forces rather than just measuring the extension for one force. Suggest why.
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(1)
The diagram below shows some of the data obtained by the student.
 
(c)  Complete the diagram above by plotting the missing data from the table above.
Draw the line of best fit.
The table above is repeated here to help you answer this question.
 
Force in N	Extension in cm	
0	0.0	
2	3.5	
4	8.0	
6	12.5	
8	16.0	
10	20.0	
(2)
(d)  Write down the equation that links extension, force and spring constant.
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(1)
(e)  Calculate the spring constant of the spring that the student used.
Give your answer in newtons per metre.
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Spring constant = ______________________ N/m
(4)
(f)  Hooke’s Law states that:
‘The extension of an elastic object is directly proportional to the force applied, provided the limit of proportionality is not exceeded.’
The student concluded that over the range of force used, the spring obeyed Hooke’s Law.
Explain how the data supports the student’s conclusion.
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(2)
(Total 16 marks)
Q2.
The diagram below shows a fork-lift truck lifting a heavy crate.

(a)  The crate weighs 11 500 N and is lifted vertically 2.60 m.
Calculate the work done to lift the crate.

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Work done = _____________________ J
(2)
The weight of the crate causes a clockwise moment of 13 800 Nm about the centre of the front wheel of the fork-lift truck.
(b)  The weight of the fork-lift truck and driver cause an anticlockwise moment. What is the minimum size of the anticlockwise moment needed so that the fork-lift truck does not topple over?
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(1)
(c)  Write down the equation which links distance, force and moment of a force.
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(1)
(d)  Calculate the distance ‘d’ marked on the diagram above.
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Distance ‘d’ = _____________________ m
(3)
(Total 7 marks)
Q3.
The graph shows changes in the velocity of a racing car.
 
(a)     Describe the motion of the racing car during:
(i)      the period labelled W; ____________________________________________
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(1)
(ii)     the period labelled Y. ____________________________________________
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(1)

(b)     Calculate the acceleration of the racing car during the period labelled X.
Show clearly how you work out your answer and give the unit.
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Acceleration = _______________________
(4)
(Total 6 marks)
Q4.
(a)     The diagram shows a rectangle made out of a sheet of cardboard.
 
Draw an X on the diagram so that the centre of the X is at the centre of mass of the rectangle.
(1)
(b)     The drawing shows a car tyre.
 
(i)      Where is the centre of mass of the tyre?
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(1)
(ii)     Explain your answer to (b)(i).
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(1)
(Total 3 marks)
Q5.
(a)    The diagram shows the forces acting on a parachutist in free fall.
 
The parachutist has a mass of 75 kg.
Calculate the weight of the parachutist.
 
gravitational field strength = 10 N/kg	
Show clearly how you work out your answer and give the unit.
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Weight = __________________________
(3)
(b)     In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
The graph shows how the vertical velocity of a parachutist changes from the moment the parachutist jumps from the aircraft until landing on the ground.
 
Using the idea of forces, explain why the parachutist reaches a terminal velocity and why opening the parachute reduces the terminal velocity.
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(6)
(c)     A student wrote the following hypothesis.
‘The larger the area of a parachute, the slower a parachutist falls.’
To test this hypothesis the student made three model parachutes, A, B and C, from one large plastic bag. The student dropped each parachute from the same height and timed how long each parachute took to fall to the ground.
 
(i)      The height that the student dropped the parachute from was a control variable.
Name one other control variable in this experiment.
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(1)
(ii)     Use the student’s hypothesis to predict which parachute, A, B or C, will hit the ground first.
Write your answer in the box. 
Give a reason for your answer.
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(2)
(Total 12 marks)
Q6.
Figure 1 shows a skier using a drag lift.
The drag lift pulls the skier from the bottom to the top of a ski slope.
The arrows, A, B, C and D represent the forces acting on the skier and her skis.
Figure 1
 
(a)     Which arrow represents the force pulling the skier up the slope?
 
Tick one box.	 	
A	 	
B	 	
C	 	
D	 	
(1)
(b)     Which arrow represents the normal contact force?
 
Tick one box.	 	
A	 	
B	 	
C	 	
D	 	
(1)
(c)     The drag lift pulls the skier with a constant resultant force of 300N for a distance of 45 m.
Calculate the work done to pull the skier up the slope.
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Work done = __________________________ J
(2)
(d)     At the top of the slope the skier leaves the drag lift and skis back to the bottom of the slope.
Figure 2 shows how the velocity of the skier changes with time as the skier moves down the slope.
Figure 2
 
After 50 seconds the skier starts to slow down.
The skier decelerates at a constant rate coming to a stop in 15 seconds.
Draw a line on Figure 2 to show the change in velocity of the skier as she slows down and comes to a stop.
(2)
(Total 6 marks)

Mark schemes
Q1.
(a)  Level 3: The method would lead to the production of a valid outcome. All key steps are identified and logically sequenced.
5−6
Level 2: The method would not necessarily lead to a valid outcome. Most steps are identified, but the method is not fully logically sequenced.
3−4
Level 1: The method would not lead to a valid outcome. Some relevant steps are identified, but links are not made clear.
1−2
No relevant content
0
Indicative content
set up a clamp stand with a clamp
hang the spring from the clamp
use a second clamp and boss to fix a (half) metre ruler alongside the spring
record the metre ruler reading that is level with the bottom of the spring
hang a 2 N weight from the bottom of the spring
record the new position of the bottom of the spring
calculate the extension of the spring
measure the extension of the spring
add further weights to the spring so the force increases 2 N at a time up to 10 N
for each new force record the position of the bottom of the spring and calculate / measure the extension
possible source of inaccuracy
not fixing the ruler in position but simply holding the ruler next to the spring
not clamping the ruler vertical
misjudging the position of the bottom of the spring
parallax error
allow any other sensible suggestion that could reasonably lead to inaccuracy in the data
allow a description that would increase accuracy
repeating the measurements is insufficient
(b)  to identify any anomalous results
allow calculate an average for the spring constant
or
to reduce the effect of random error
allow (more) accurate
to obtain an average is insufficient
to be able to draw a graph is insufficient
1
(c)  both points plotted correctly
1
correct line of best fit drawn
to pass through (0,0) and (10,20)
1
(d)  force = spring constant × extension
allow F = ke
1
(e)  extension = 0.2
allow 0.035 / 0.08 / 0.125 / 0.16
1
10 = k × 0.2
force value must match extension
this mark may be awarded if e is in cm
1
 
allow correct transformation of their chosen values
this mark may be awarded if e is in cm
1
k = 50
an answer 0.5 scores 3 marks
1
an answer of 50 scores 4 marks
(f)  the line is straight
allow the line does not curve
1
and passes through the origin
this mark is dependent on scoring the first mark
allow a correct description of direct proportionality for 2 marks
ignore the line shows they are directly proportional
1
[16]
Q2.
(a)  work done = 11 500 × 2.60
1
work done = 29 900 (J)
1
an answer of 29 900 scores 2 marks
(b)  13 800
1
(c)  moment (of a force) = force × distance
allow M = F d
1
(d)  13 800 = 11 500 × distance
1

1
distance = 1.2(0 m)
1
of an answer 1.2(0) scores 3 marks
[7]
Q3.
(a)     (i)      acceleration / speeding up 
do not accept acceleration increases
1
(ii)     constant / steady velocity
accept constant / steady speed
1
(b)     10
3
m/s2 or ms־2
reject ms2
if answer not correct then allow 1 mark for
acceleration = 
 
and allow 1 mark for 
1
[6]
Q4.
(a)     centre of X at the point where the axes cross
to within 1 mm in any direction
1
(b)     (i)      (at / in the) centre (of the tyre)
or unambiguously shown on the diagram
1
(ii)     (this is) where axes of symmetry (of the tyre) cross / intersect / meet
or point at which the mass of the tyre seems to be (concentrated)
1
[3]
Q5.
(a)     750
allow 1 mark for correct substitution, ie 75 × 10 provided no subsequent step shown
2
newton(s) / N
do not accept n
1
(b)     Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. 
Examiners should also refer to the Marking Guidance, and apply a ‘best-fit’ 
approach to the marking.
          0 marks
No relevant content.
          Level 1 (1-2 marks)
There is a brief attempt to explain why the velocity / 
speed of the parachutist changes.
or 
the effect of opening the parachute on velocity/speed is given.
          Level 2 (3-4 marks)
The change in velocity / speed is clearly explained in terms of force(s)
or
a reasoned argument for the open parachute producing a lower speed.
          Level 3 (5-6 marks)
There is a clear and detailed explanation as to why the parachutist 
reaches terminal velocity 
and
a reasoned argument for the open parachute producing a lower speed
examples of the physics points made in the response to explain 
first terminal velocity
•        on leaving the plane the only force acting is weight (downwards)
accept gravity for weight throughout
•        as parachutist falls air resistance acts (upwards)
accept drag / friction for air resistance
•        weight greater than air resistance 
or
resultant force downwards
•        (resultant force downwards) so parachutist accelerates
•        as velocity / speed increases so does air resistance
•        terminal velocity reached when air resistance = weight
accept terminal velocity reached when forces are balanced
to explain second lower terminal velocity
•        opening parachute increases surface area
•        opening parachute increases air resistance
•        air resistance is greater than weight
•        resultant force acts upwards / opposite direction to motion
•        parachutist decelerates / slows down
•        the lower velocity means a reduced air resistance
air resistance and weight become equal but at a lower (terminal) velocity
6
(c)    (i)       any one from:
•        mass of the (modelling) clay
accept size/shape of clay size/amount/volume/shape of clay
accept plasticine for (modelling)clay
•        material parachute made from
accept same (plastic) bag
•        number / length of strings
1
(ii)     C
reason only scores if C is chosen
1
smallest (area) so falls fastest (so taking least time)
accept quickest/quicker for fastest
if A is chosen with the reason given as ‘the largest area so falls slowest’ this gains 1 mark
1
[12]

Q6.
(a)     D
1
(b)     C
1
(c)     W = 300 × 45
1
W = 13 500
1
allow 13 500 with no working shown for 2 marks
(d)     straight line drawn from 13 m / s to 0 m / s
1
finishing on x-axis at 65 s
1
[6]