Question

a 0.311 kg tennis racket moving 30.3 m/s east makes an elastic collision with a 0.0570 kg ball moving 19.2 m/s west. find the velocity of the tennis ball after the collision.

Answer 1

Answer:

15.0 m/s

Explanation:

When elastic collision occurs, the final velocities, v of the bodies are obtained by

$v_1=\frac {(m_1-m_2)u_1}{m_1+m_2}+ \frac {2m_2u_2}{m_1+m_2}$

$v_2=\frac {(m_2-m_1)u_2}{m_1+m_2}+ \frac {2m_2u_1}{m_1+m_2}$

Where u and m denote initial velocities and mass while the subscripts 1 and 2 are for tennis ball and the other ball

Substituting 0.311 for mass of tennis, 0.0570 for mass of the other ball, 30.3 m/s for velocity of tennis ball and -19.2 m/s  

$v_1=\frac {(0.311-0.0570)\times 30.3}{0.311+0.0570}+ \frac {2\times 0.0570\times -19.2}{0.311+0.0570}= 20.91359+ -5.94783= 14.96576 m/s\approx 15.0 m/s$