A firework shell of total mass is initially at rest when it explodes into two pieces

PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A firework shell of total mass

0.70\,\text{kg}

is initially at rest when it explodes into two pieces. A

0.20\,\text{kg}

fragment flies due east at

40\,\text{m/s}

, while the remaining

0.50\,\text{kg}

fragment moves in the opposite direction. Calculate the speed of the heavier fragment.