Chapter 27 : Collision of Elastic Bodies 571
- A ball moving with a velocity of 2 m/s, hits a smooth fixed plane at an angle of 30°. If the
coefficient of restitution is 0.8, find the angle which the ball makes with the line of impact
after hitting. Also find the velocity of the ball after hitting. (Ans. 65.2° ; 1.91 m/s)
QUESTIONS
- Define the terms ‘collision of elastic bodies’. Discuss the phenomenon of collision.
- What are various types of impacts? Discuss any one of them.
- Define the coefficient of restitution.
- If m 1 and m 2 are the masses of two bodies, u 1 and u 2 , v 1 and v 2 are the velocities of the
bodies before and after the impact respectively and e the coefficient of restitution, show
that the loss of a kinetic energy due to direct impact is given by :
12 22
12
12
0.5 ( ) (1 – )mm
uu e
mm+
+- What is the difference between the impact of two bodies and the impact of a body on a
fixed plane?
OBJECTIVE TYPE QUESTIONS
- The total momentum of two bodies remains constant after collision or any other mutual
action. This is known as
(a) Law of Conservation of Momentum
(b) Newton’s Law of Collision of Elastic Bodies
(c) both (a) and (b)
(d) none of them - The coefficient of restitution for inelastic bodies is
(a) zero (b) between zero and one (c) one - The bodies which rebound after impact are called
(a) inelastic bodies (b) elastic bodies
(c) neither elastic or inelastic bodies - The loss of kinetic energy during elastic impact is zero.
(a) Yes (b) No - The loss of kinetic energy due to direct impact of two bodies depends on
(a) the mass of two bodies
(b) the initial velocities of two bodies
(c) the final velocities of two bodies
(d) Both (a) and (b) - If a lead ball with a certain velocity is made to strike a wall, it does not rebound. But if a
rubber ball of same mass and velocity strikes the same wall, it rebounds. Select correct
reason from the followig :
(a) the change in momentum suffered by the rubber ball is more than that of the lead ball.
(b) the change in momentum suffered by the lead ball is more than that of the rubber ball.
(c) both (a) and (b).
(d) none of the above.
ANSWERS
- (a) 2. (a) 3. (b) 4. (a) 5. (d) 6. (a)
Top