Answer to Question #169890 in Physics for Andu

Question

EXERCISE 12

 The cannon with mass m = 450 kg shoots horizontally. The mass of the projectile is m = 5 kg and the speed it takes is v = 450 m / s.

 How fast will the ball bounce during the shooting?

 a) 4 m / s b) 3m / s c) 5m / s d) 2m / s

Answer 1

According to the momentum conservation law:

$$m_cv_c = m_pv_p$$

where $m_c = 450kg, m_p = 5kg$ are the masses of the cannon and the projectile respectively, and $v_c , v_p = 450m/s$ are their speeds respectively. Expressing $v_c$, obtain:

$$v_c = \dfrac{m_pv_p}{m_c}\\ v_c = \dfrac{5kg\cdot 450m/s}{450kg} = 5m/s$$

Answer. 5 m/s.