Question

A 7.0 g bullet is fired horizontally into a 1.5 kg block of wood suspended by a thread. The bullet emerges from the block with a speed of 195 m/s, and the block rises to a maximum height of 12 cm.

Find the initial speed of the bullet.

Answer 1

First calculate the momentum of the block with the bullet hole in it. Ignore the mass loss of wood, since they provide no information on it.

0.007*Vb = Total Momentum after bullet passes through
= 195*.007 + sqrt(2*g*H)*1.5

Solve for Vb, the initial bullet velocity
H = 0.12 m
sqrt(2*g*H) is the block velocity after the bullet passes through but before it swings upwards.

Answer 2

À 7gram billet fired intio à 1.5kg palliatif pendules thé billet émerge in thé block WIth à speed 200m/s and thé block rises to maximum Wright of 12cm fond thé initial speed of thé billet