2 John is at the top of a cliff, looking out over the sea. He throws a rock, of mass 3 kg , horizontally with a velocity of \(4 \mathrm {~m} \mathrm {~s} ^ { - 1 }\).
The rock falls a vertical distance of 51 metres to reach the surface of the sea.
- Calculate the kinetic energy of the rock when it is thrown.
- Calculate the potential energy lost by the rock when it reaches the surface of the sea.
- Find the kinetic energy of the rock when it reaches the surface of the sea.
- Hence find the speed of the rock when it reaches the surface of the sea.
- State one modelling assumption which has been made.
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