A rock is at rest on a tall cliff. Then a strong wind blows the rock off the cli

Question

A rock is at rest on a tall cliff. Then a strong wind blows the rock off the cliff. When does the rock have maximum kinetic energy?

while at rest on the cliff, just before it strikes the ground beneath the cliff, after it comes to a rest on the ground beneath the cliff, just after it falls off the cliff.

The amount of power that a person uses to climb a hill is described as _____.

average power

gravitational power

momentary power

instantaneous power

A force is applied to an object in a direction that is perpendicular to the object's displacement. The work performed by the force on the object is ______.

zero

positive

negative

Explanation / Answer

First question -

The correct option is 'just before it strikes the ground beneath the cliff'.

Explanation -

The kinetic energy shall be maximum when the potential energy is minimum. Just before striking the ground, the rock has minimum P.E., So, it has maximum kinetic energy.

Second question -

The correct option is 'average power'.

Third question -

Work performed by the force is ZERO.

Because, work done, W = F*dcos theta

here theta = 90 degree. So, cos theta = 0

So, W = 0

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