Grade C Forces, motion and energy calculations Name:
Q6.
.
A child goes out to visit a friend.
The graph shows the child’s journey.
(a)
Calculate the child’s average speed for the whole journey.
[Show your working and give the units in your answer.]
.....................................................................................................................................
.....................................................................................................................................
(3)
(b)
How many times faster is the child travelling in part A of the graph than in part C?
[You should show how you obtained your answer.]
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.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 5 marks)
Page 1
Q7.
(a)
The arrows in the diagram represent the size and direction of the forces on a
space shuttle, fuel tank and booster rockets one second after launch. The longer the
arrow the bigger the force.
(i)
Describe the upward motion of the space shuttle one second after launch.
...........................................................................................................................
(1)
(ii)
By the time it moves out of the Earth’s atmosphere, the total weight of the space shuttle,
fuel tank and booster rockets has decreased and so has the air resistance.
How does this change the motion of the shuttle? (Assume thrust force doesn’t change).
..................................................................................................................... (1)
(b)
The space shuttle takes 9 minutes to reach its orbital velocity of 8100 m/s.
(i)
Write down the equation that links acceleration, change in velocity and time taken.
...................................................................................................................... (1)
(ii)
Calculate, in m/s2, the average acceleration of the space shuttle during the first
9 minutes of its flight. Show clearly how you work out your answer.
...........................................................................................................................
...........................................................................................................................
average acceleration = .............................................. m/s2
(2)
(iii)
How is the velocity of an object different from the speed of an object?
.........................................................................................................................
(1)
(Total 6 marks)
Page 2
Q8.
A cyclist accelerates from a set of traffic lights.
The driving force of the back tyre on the ground is 250 N.
(a)
How much work is done by this force when the cyclist travels 5 metres?
(Show your working.)
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Answer ............................ joules (J)
(b)
(2)
What happens to the energy transferred by this force?
.....................................................................................................................................
....................................................................................................................(2)
(Total 4 marks)
Q9.
(a)
The diagram shows a car travelling at a speed of 12 m/s along a straight road.
i) Use the correct to calculate the momentum of the car. Mass of the car = 900 kg
Show clearly how you work out your answer.
...........................................................................................................................
...........................................................................................................................
Momentum = .............................. kg m/s
(2)
(Total 2 marks)
Q10.
(a)
The diagram shows an athlete at the start of a race. The race is along a
straight track.
In the first 2 seconds, the athlete accelerates constantly and reaches a speed of 9
m/s.
Page 3
(i)
Use the correct equation to calculate the acceleration of the athlete.
Show clearly how you work out your answer. Give the unit
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
Acceleration = ..............................
(3)
(Total 3 marks)
Q12.
A sky-diver steps out of an aeroplane.
After 10 seconds she is falling at a steady speed of 50m/s.
She then opens her parachute.
After another 5 seconds she is once again falling at a steady speed.
This speed is now only 10m/s.
(a)
Calculate the sky-diver’s average acceleration during the time from when she opens
her parachute until she reaches her slower steady speed. (Show your working.)
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
(Total 3 marks)
Q13.
The picture shows an advert for an electric mobility scooter.
(a)
kg.
The mass of the scooter driver is 80
Use the correct equation to calculate the
kinetic energy of the scooter and driver
when they are travelling at maximum
speed. Include the unit.
(3)
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Page 4
Grade C Forces, motion and energy calculations Mark Scheme
M6 (a)
evidence of
speed =
(travelled)
or
or
gains 1 mark
but or any correct calculation of gradient
(except when zero) gains 2 marks
or 2
gains 1 mark
units metres per second or m/s or ms-1
(not mps)
for 1 mark
3
(b)
evidence of calculating the two speeds
(
and
or
5 and 2)
(evidence of this may be in (a))
or
noting distances travelled in same time (20 secs) i.e. 100m and 40m but 2.5
gains 2 marks
2
[5]
M7.
(a)
(i)
accelerating
accept getting faster
accept speed / velocity increasing
1
(ii)
acceleration increases
accept velocity / speed increases more rapidly
do not accept velocity / speed increases
1
(b)
(i)
acceleration =
accept a =
or a =
Page 5
do not accept velocity for change in velocity
do not accept change in speed
do not accept a =
1
(ii)
15
allow 1 mark for an answer of 900 or for correct use of 540
seconds
2
(iii)
velocity includes direction
accept velocity is a vector (quantity)
accept converse answer
1
[6]
M8.
(a)
[NB e.c.f not allowed from incorrect formula]
work done = force × distance or 250 × 5
gains 1 mark
but
1250
gains 2 marks
2
(b)
•
(mainly) transferred as kinetic / movement energy
[not makes bike move]
•
(some) lost / wasted / transferred as heat / sound
or
used to overcome friction / air resistance
each  for 1 mark
2
[4]
Page 6
M9.
(a)
(i)
10800
allow 1 mark for correct substitution i.e. 900 × 12
2
[2]
M10.
(a)
(i)
4.5 m/s2
allow 1 mark for correct substitution i.e. 9 ÷ 2 1 mark for unit
3
[3]
M12
(a)
evidence of
or
gains 1 mark
(credit 50/10 or 5 with 1 mark) NOT 40/10 or
50/5
but 8 [N.B. negative not required]
gains 2 marks
units metres per second per second or (metres per second squared or m/s²)
for 1 mark
[3]
M13.
375 J
1 mark for correct substitution, 1 mark for correct unit –do
not accept lower case j
1 mark for an answer = 250
1 mark for an answer = 125
2
[7]
Page 7