Question

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

The total momentum is

$$m_1\vec v_1+m_2\vec v_2=-0.256\text{ kg}·\text{m/s}.$$