| a. |
The
diagram shows a set up for the Monkey and Hunter Experiment.
i)
Explain why the metal can falls as soon as the bullet hits the aluminium
foil. |
6
marks |
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The metal can is supported by the magnetic force from the
electromagnet. When the aluminium foil breaks, the circuit is open; current
stops flowing and the magnetic force vanishes. Thus, the metal can falls
immediately. |
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ii)
A student sets up the apparatus in a hurry and finds it difficult to hit
the metal can with the bullet. Suggest two ways to rectify the possible
errors in his set up. |
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The possible faults in his experiment are:
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the gun (tube from which bullet is fired) and the metal can are not at
the same level
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the gun is not arranged horizontally
To rectify problem,
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arrange the metal can so that it is at the same level as the aluminium
foil
-
arrange the gun horizontally at the same level as the aluminium foil
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iii)
Suppose improvements have been made to the set up. State the difference
if the bullet is fired with a higher speed. Explain your answer with the
aids of diagrams. |
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When the bullet is fired with a higher speed, the metal
can will be hit at a higher level. The following diagrams show the
difference: |
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| b. |
A
stone is projected with a horizontal speed u from a table. Find expressions
for the horizontal and vertical displacements from the edge of table at
time t after the projection. Hence, show that the path of the stone in
air is parabolic. |
4
marks |
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1 |
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The horizontal speed of the stone is always u. So, after
time t, the horizontal displacement is
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The vertical motion start from rest. After time t,
the vertical displacement is
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Eliminating t from the two equations,
The equation is in the form of a parabola. |
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| c. |
If
the table in (b) is at a height h above the ground, find the velocity with
which the stone hits the ground, stating both the magnitude and direction. |
6
marks |
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1 |
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When the stone hits the ground, the horizontal component
of the velocity is
The vertical component is
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Thus, the magnitude of the final velocity is
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The direction of the velocity is given by
This is the angle that v makes with the vertical. |
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