Question

is an object of mass 20 kg is dropped from a height of 4 metre find the prime potential energy and kinetic energy in each case is​

Answer 1

Given

An object of mass 20 kg

Height = 4m

Taking g as 10 m/s²

Now, initial potential energy = mgh

⇒ 20 × 4 × 10

⇒ 800 J

Initial kinetic energy = 1/2 × mv²

Here, velocity is 0 at first, hence initial kinetic energy = 0 Joules

Now, final potential energy = mgh

At the final moment, the object will drop on the earth surface making h = 0

Hence, final potential energy = 0 Joules

Now, we know that, energy of an object stays constant. That is, energy is conserved. So,

initial potential + initial kinetic = final potential + final kinetic

⇒ 800 + 0 = 0 + final kinetic

⇒ final kinetic energy = 800 J