Question

A 15g bullet is shot into a 5085g wooden block standing on a frictionless surface. The block, with the bullet in it, acquires a velocity of .94m/s. Calculate the velocity of the bullet before striking the block.

Answer 1

To develop this problem we will apply the concepts related to the conservation of momentum. For this purpose, the initial momentum will be equivalent to the initial momentum of the two objects when they have the same speed. Mathematically this can be expressed as,

$m_bv_b + m_wv_w = (m_b+m_w)v$

Where,

$m_b$ = Mass of bullet

$v_b$= Velocity of bullet

$m_w$= Mass of wooden block

$v_w =$Velocity of Wooden block

Inititally $v_w = 0$ then we have that the expression can be rearrange to find the velocity of the bullet,

$v_b = \frac{(m_b+m_w)v}{m_b}$

Replacing with our values

$v_b = \frac{(15+5085)(0.94)}{15}$

$v_b = 319.6m/s$

Therefore the velocity of the bullet before striking the block is 319.6m/s