7 Diagram
8.1 shows the model of a water rocket made from a drinking bottle.
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(a)
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Name the Physics Principle used to launch the rocket into
the air.
Conservation
of momentum
……………………………………………………………………………….
[1 mark]
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(b)
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Explain how the
rocket can move upwards.
When the piston is pressed ,air is compressed and
pressure increases
When the pump is removed ,water will be ejected at a high
velocity resulting in a momentum backwards
A upward momentum of the same magnitude will be produced
Rocket
moves upwards
……………………………………………………………………………….
……………………………………………………………………………….
……………………………………………………………………………….
[ 3 marks]
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(c)
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When the rocket is
disconnected from the pump, the rocket moves upwards and 50 g of water is
ejected with a velocity of 5 m s-1. The mass of the empty rocket
is 70 g. Calculate the velocity of the rocket.
70 v =
50 x 5
v
= 3.57 m s-1
[2 marks]
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(d)
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Suggest two
modifications that can be done to the rocket so that it can go higher into
the air
Shape should be more aerodynamic
Reduce
the mass of the rocket
[2 marks]
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