A(n) 17.4 g bullet is shot into a(n) 5506 g wooden block standing on a frictionless sur-
face. The block, with the bullet in it, acquires
a speed of 1.61 m/s.
Calculate the speed of the bullet before
striking the block..
Answer in units of m/s.

The initial speed of the bullet = v₁= 511.07 m/s

Given

17.4 g bullet

5506 g wooden

The velocity of the block+bullet :1.61 m/s

Required

The initial speed

Solution

Momentum

m₁v₁+m₂v₂=m₁v₁'+m₂v₂'

v₂=0 ⇒block at rest

v₁'=v₂'=1.61 m/s

the equation becomes :

m₁v₁=(m₁+m₂)v'

17.4v₁=(17.4+5506)1.61

v₁= 511.07 m/s

c. newton's third law of motion