Question

A small bomb explodes in 2 pieces. A first piece of 1.20 kg moves at 18.0 m / s to the left. What is the speed in m / s of the second piece with a mass of 1.60 kg?

Answer 1

Let's choose the rightward as a positive direction. Then, applying the law of conservation of momentum, we have:

$$p_i=p_f,$$ $$0=-m_1v_1+m_2v_2,$$ $$v_2=\dfrac{m_1v_1}{m_2}=\dfrac{1.20\ kg\cdot 18.0\ \dfrac{m}{s}}{1.60\ kg}=13.5\ \dfrac{m}{s}.$$

The sign plus means that the second piece of the exploded bomb moves to the right.

Answer:

$v_2=13.5\ \dfrac{m}{s},$ to the right.