Question

a body of mass 20kg is lifted up by 10m. calculate its potential energy. if this body is allowed to fall, find its kinetic energy just before it touchesthe ground. take g=10m/ssq

Answer 1

given,  

             m=20kg,

             h=10 metre

therefore, potential energy=mgh

                                            =20*10*10

                                             =2000J(joule)

and kinetic energy of the body just before it reach the ground is=half of mv square

                                                                                                                   =

                                                                                                                   =half*20kg*velocity square

                                                                                                                    =10 kg*velocity square

                             

Answer 2

The energy of a body due to its position is called potential energy.

The energy of a body due to its motion is called kinetic energy.

Solution :

Mass of body = 20kg

It is lifted by = 10m

g = 10 m/sec^2

Potential energy = ?

Kinetic energy = ?

Gravitational potential energy = mgh = 20 × 10 × 10 = 2000 J

Kinetic energy = 1mv^2/2

Let's find v^2.

v^2 = u^2 +2as

v^2 = 2as

v^2 = 200 m/s

Putting the values.

KE = 1×20×200/2

= 2000 J