Q. 174.8( 4 Votes )

# A 10 kg ball is dropped from a height of 10m. Find

(a) the initial potential energy of the ball ,

(b) the kinetic energy just before it reaches the ground

(c) the speed just before it reaches the ground.

Answer :

Given data

Mass of ball (m)= 10kg

Height(h) = 10m

(a) potential energy = mgh

= 10 (kg)× 10 (m/s^{2}) × 10 (m)

=1000 (J)

(b)when the ball reaches the ground the gravitational potential energy changes to kinetic energy

So, kinetic energy gained= 1000(J)

__If we neglect the air resistance__

(c) We know that Kinetic Energy = and from above data we have kinetic energy as 1000 J and mass of ball (m) as 10kg ,hence on equating for velocity we will get velocity as

V = substituting Kinetic Energy = 1000 J and mass as 10 kg ,we have

Velocity = = = 14.14 m/s

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