Question

A 15-kg rock falls from a cliff at a height of 140 m to a cliff that is 36 m above the ground. How fast is the rock falling when it strikes the lower cliff

Answer 1

Mass = 15 kg
initial height = 140 m
final height = 36 m
gravity =10 m s-2
then,potential energy = mass x gravity x height
potential energy of initial height =15 x 10 x 140
=21,000 (i)
Potential energy of final height = 15 x 10 x 36
=5,400
potential energy of final height-potential energy of initial height
=21,000-5,400=15,600 J

Answer 2

Answer:

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