Advertisements
Advertisements
Question
A ball of mass 50 g falls from a height of 2m and rebounds from the ground to 1.6 m. Find:
(i) The potential energy possessed by the ball when initially at rest.
(ii) The kinetic energy of the ball before it hits the ground.
(iii) The final potential energy of the ball.
(iv) The loss in kinetic energy of the ball on collision. (Take: g = 10N kg−1)
Advertisements
Solution
Given : m = 50g = `50/1000`kg = 0.05 kg,
g = 10N kg−1,
h1 = 2m = 1.6 m.
(i) Initial potential energy possessed by the ball = mgh1
= 0.05 × 10 × 2 = 1.0 J.
(ii) The K.E. of the ball before it hits the ground
= Initial potential energy possessed by the ball
= 0.1 J
(iii) The final potential energy of the ball = mgh2
= 0.05 × 10 × 1.6
= 0.8 J.
(iv) The kinetic energy of the ball after striking the ground
= Final potential energy of the ball = 0.8 J
RELATED QUESTIONS
Select the correct alternatives
A ball rolling on the ground possesses
A light mass and a heavy mass have equal momentum. Which will have more kinetic energy?
(Hint : Kinetic energy K = P2/2m where P is the momentum.)
State the energy changes in the following case while in use:
an electric toaster.
Name three non-renewable sources of energy.
What do you understand by mechanical energy?
Give one example when:
Electric energy changes to mechanical energy.
Draw a diagram to show the energy changes in an oscillating simple pendulum. Indicate in your diagram how the total mechanical energy in it remains constant during the oscillation.
A ball of mass 200 g falls from a height of 5 m. What will be its kinetic energy when it just reaches the ground? (g = 9.8 m s−2)
Use your brain power!
Why do tablets of camphor decrease in size day by day?
In which states is water found in nature?
