Question

a body of mass 10kg is kept at a height of 5m. lt is allowed to fall and reach the ground.
1) what is the total mechanical energy possessed by the body at height of 2m assuming it is a frictionless medium
2) what is the kinetic energy possessed by the body just before hitting the ground? take g=10m/s²​

Answer 1

In this question,one must first of all know the formulas of calculating both kinetic,potential and mechanical energy.

Representing Kinetic Energy with K, potential with P and mechanical with M, we have the following equations:

K=1/2mv^2 P=mgh M=K+P

Where m is the mass,g is the gravitational force, and h is the height.

So M=1/2mv^2+mgh but we dont have the value of v.

At a height of 2.5m the kinetic energy is equal to potential energy.

1/2mv^2=mgh, where m=10,g=10 h=2.5m

5v^2=250, v^2=50 and remember M=K+P, 1/2mv^2+mgh

=[1/2*10*50]+[10*10*2]

=250+200, =450

[1] 450J

Kinetic Energy=1/2mv^2

1/2*10*10^2, 5*10*100

=5000

[2] 5000J