A 60-g bullet was fired horizontally into a stationary 50-kg sandbag suspended on a rope 900 mm long, as shown in Fig. 7-29. It was calculated from the observed angle θ that the bag with the bullet embedded in it swung to a height of 30 mm. What was the speed of the bullet as it entered the bag?
Let
Momentum of system before impact = momentum of system after impact:
0.06 v_{2}+0=(0.06+50) \times 0.767
from which v_{1}=\underline{640 \mathrm{~m} / \mathrm{s}} .