A billiard ball moving at 550 ms strikes a stationary ball o

  A billiard ball moving at 5.50 m/s strikes a stationary ball of the same mass. After the collision, the first ball moves at 4.90 m/s, at an angle of 27.0° with respect to the original line of motion.

(a) Find the velocity (magnitude and direction) of the second ball after collision.
m/s
° (with respect to the original line of motion, include the sign of your answer; consider the sign of the first ball\'s angle)(b) Was the collision inelastic or elastic?

3

inelastic elastic    

Solution

v_1i = 5.50 - (4.90 * cos 27) = 1.1341 m/s

v_1f = 5.50 - (4.90 * sin 27) = 3.28 m/s

v_2f = sqrt [1.1341² + 3.28²]

= 3.47 m/s

phi = tan^-1 [3.28 / 1.1341]

= 70.91 deg

The collision is indeed elastic