Solutions:
According to the questions –
Mass of ball is 0.5 kg
Initial velocity is 5 m / s
Using the expression of the kinetic energy, we have –
Initial kinetic energy = 1 / 2 × mass × (velocity)2
= 1 / 2 × 0.5 × (5)2 = 1 / 2 × 0.5 × 25
Initial kinetic energy = 6.25 J
Final velocity of the ball is 3 m / s
Again, Using the expression of the kinetic energy, we have –
Final kinetic energy of the ball = 1 / 2 × mass × (velocity)2
= 1 / 2 × 0.5 × (3)2 = 1 / 2 × 0.5 × 9
= 2.25J
So, the change in the kinetic energy of the ball is given as follows
= 2.25 J – 6.25 J = – 4J
Therefore, there is a decrease in the kinetic energy of the ball.