Question

A bullet moving at a speed of 152 m/s passes through a plank of wood at 128m/s. Another bullet moving at 97m/s passes through the same plank at what speed?

Answer 1

Answer:

The speed of the plank is 81.68 m/s

Explanation:

Given that,

Speed of bullet = 152 m/s

Speed of wood = 128 m/s

Speed of another bullet = 97 m/s

We need to calculate the speed of plank

Using conservation of momentum

$m_{1}u_{1}=(m_{1}+m_{2})v$

Where,

u = initial velocity

v = final velocity

$152m_{1}=(m_{1}+m_{2})128$....(I)

$m_{1}97=(m_{1}+m_{2})v$....(II)

From equation(I) and equation(II)

$\dfrac{152}{97}=\dfrac{128}{v}$

$= \dfrac{128\times97}{152}$

$v=81.68\ m/s$

Hence, The speed of the plank is 81.68 m/s