Question

An object of mass 40 kg is raised to a height of 5m above the ground what is its potential energy? If the object is allowed to fall, find its kinetic energy when it has travelled a distance of 2m from the top.

Answer 1

1) Mass of object = 40kg

Height up to which the object is raised = 5m

Potential Energy = mgh

= (40)(9.8)(5)

= 1960 Joules

2) Under free fall

acceleration = 9.8m/s²

Initial velocity = 0

Height/ Distance Covered in y-direction = 2m

v²-u² = 2as

v²-0 = 2(9.8)(2)

v² = 39.2

v = 6.26 m/s

Kinetic Energy = 1/2 (m)(v)²

1/2( 40)(39.2)

7.84 J