1. This question is about the kinematics of an elevator (lift).
(a) Explain the difference between the gravitational mass and the inertial mass of an object.
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(3)
An elevator (lift) starts from rest on the ground floor and comes to rest at a higher floor. Its
motion is controlled by an electric motor. A simplified graph of the variation of the elevator’s
velocity with time is shown below.
v elo city / m s – 1
0 .8 0
0 .7 0
0 .6 0
0 .5 0
0 .4 0
0 .3 0
0 .2 0
0 .1 0
0 .0 0
0 .0 1 .0 2 .0 3 .0 4 .0 5 .0 6 .0 7 .0 8 .0 9 .0 1 0 .0 11 .0 1 2 .0
tim e / s
The elevator is supported by a cable. The diagram below is a free-body force diagram for when
the elevator is moving upwards during the first 0.50 s.
ten sio n
w eig h t
1
(b) In the space below, draw free-body force diagrams for the elevator during the following
time intervals.
(i) 0.50 to 11.50 s (ii) 11.50 to 12.00 s
(3)
A person is standing on weighing scales in the elevator. Before the elevator rises, the reading on
the scales is W.
(c) On the axes below, sketch a graph to show how the reading on the scales varies during the
whole 12.00 s upward journey of the elevator. (Note that this is a sketch graph – you do
not need to add any values.)
read in g o n scales
0 .0 0
0 .0 1 .0 2 .0 3 .0 4 .0 5 .0 6 .0 7 .0 8 .0 9 .0 1 0 .0 11 .0 1 2 .0
tim e / s
(3)
2
(d) The elevator now returns to the ground floor where it comes to rest. Describe and explain
the energy changes that take place during the whole up and down journey.
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(4)
(Total 13 marks)
3
2. This question is about vectors.
A student sets up the apparatus shown below to investigate forces.
sp rin g
b alan ce B
sp rin g
b alan ce B
1 0 N w eig h t
The weight of 10.0 N is suspended from spring balance A by means of a light string. Spring
balance B is also attached to the string. The spring balance B is pulled horizontally as shown.
(a) Using the grid on the diagram, draw a scale diagram to determine the readings on each of
the spring balances.
Reading on spring balance A: ...................................................................................
Reading on spring balance B: ...................................................................................
(4)
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(b) Suggest why it is not possible for the whole length of the string joining spring balances A
and B to be horizontal with the weight still suspended.
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(1)
(Total 5 marks)
