Question

Weylan is at the county fair playing some of the games. At one booth, he throws a 0.75-kg ball forward with a velocity of 21.0 m/s in order to hit a 0.50-kg bottle sitting on a shelf, and when he makes contact the bottle goes flying forward at 20.0 m/s. What is the velocity of the ball after it hits the bottle?

Answer 1

Given that the mass of the ball is m1= 0.75 kg and initial velocity, u1 = 21 m/s.

This ball strikes a bottle of mass, m2= 0.5 kg, and the initial velocity of the bottle, u2 = 0 m/s.

We have to find the final velocity of the ball, v1 after collision with the bottle having final velocity, v2 = 20 m/s

Momentum is conserved during a collision. So, the equation of momentum can be written as

$m1u1+m2u2=m1v1+m2v2$

Substituting the values, v1 will be

$\begin{gathered} v1=\frac{m1u1+m2u2-m2v2}{m1} \\ =\frac{0.75\times21+0.5\times0-0.5\times20}{0.75} \\ =7.67\text{ m/s} \end{gathered}$

Thus, the velocity of the ball is 7.67 m/s.