Question

a body of mass 20 kg is raised to the top of a building 15 m high and then dropped freely under gravity
1) find out the work is done in rasing the body to the top of the building
2) what was the value of gravitational potential energy at the top of the building
3) by what factor will the gravitational potential energy of the same body increase, if it is raised to the top of multi- story building 45 metre high
4) when will the kinetic energy of the body be maximum​

Answer 1

Explanation:

1) work done in raising the body = mgh

20×10×15

=3000 j

2) gravitational potential energy= work done

so 3000 j.

3) if h=45 then

gravitational potential energy= 20×45×10

= 9000j

so the factor it raise by is 3

4) as the velocity will be maximum when the body is just near the ground or to be striken

so kinetic energy is also maximum at that point .

k.e.= 1/2mv²

Answer 2

Answer:

3000J, 3000J, 9000J, 1/2mv²