View Full Version : Billiard ball
 
 aruppcb
Apr 7, 2014, 01:04 AM
A billiard ball moving at a speed of 2.2 m/s strikes an identical stationary ball a glancing blow.After the collision,one ball is found to be moving at a speed of 1.1 m/s in a direction making a 60° angle with the original line of motion.i) Find the velocity of other ball.ii) Can the collision be inelastic,given these data? Justify your answer.
 CWH68
Apr 20, 2014, 09:23 AM
Hint: Use the law of conservation of momentum.
 
m1v*1 + m2v*2 before = m1v*1 + m2v*2 after.
 
Here, v* denotes the velocity vector, and v denotes the speed.
 
In an elastic collision, kinetic energy is conserved. i.e. 
 
(m1v1^2)/2  + (m2v2^2)/2  before = (m1v1^2)/2 + (m2v2^2)/2 after.
 
In an inelastic collision, the total kinetic energy after is less than 
the total kinetic energy after.
 
In a completely inelastic collision, the balls would stick together afterwards.
 CWH68
Apr 20, 2014, 09:27 AM
In an inelastic collision, the total kinetic energy after is less than the total kinetic energy before the collision.  My bad. Hope this helps.
-CWH :-)