Answer:
Explanation:
During upward or downward motion of ground the kinetic energy and potential energy are interchangeable.
At a certain height h potential energy= P.E
P.E= mgh
Since h=60 m
So P.E= m× 9.8m/s²× 60m
P.E= 588m
Where m is the mass of the object and is unknown.
At height of 60 meters the Kinetic energy K.E of the body is 20,000.
Since K.E = (1/2)mv²
20,000= (1/2)mv²
v= √(40000/m)
By using the third equation of motion
v²= u²+ 2gh
Here u is the initial velocity and v is the final velocity
The initial velocity during motion under the effect of gravity is always zero
So
v =√(2gh)
v=√(2×9.8m/s²×60m)=34.3 m/s
By using this value of v in the above equation
v²=40,000/m
Or
m= 40, 000/v²
m=34kg
Hence potential energy
P.E= 588×34
=19991 which is almost equal to K.E.
