Question

6. A baseball of mass 0.145 kg is moving in the +y-direction with a speed of 1.30 m/s, and a tennis ball of mass 0.0570 kg is moving in the – 𝑦- direction with a speed of 7.80 m/s. What are the magnitude and direction of the total momentum of the system consisting of the two balls?

Answer 1

Apply momentum conservation:

$$m_1\vec v_1+m_2\vec v_2=\vec p_T,\\\space\\ 0.145·1.3+0.057·(-7.8)=-0.256\text{ kg}·\text{m/s}^2.$$

The total momentum of the system is in -y direction.