Question

A $1000kg$ moveable cannon traveling at $5m/s$ fires a $5kg$ cannonball forward at $50m/s$ relative to the cannon.
What is the recoil velocity of the cannon with respect to the ground?

• A. $5m/s$ to the right
• B. Less than $5m/s$ to the right
• C. Stationary
• D. Less than $5m/s$ to the left
• E. $5m/s$ to the left

Answer 1

The correct option is A $5m/s$ to the right

The speed of cannnonball relative to the cannon=$50m/s$

The speed of cannon=$5m/s$

Thus speed of cannnonball relative to the ground=$55m/s$

From conservation of momentum,

$m_{cannon}{v}_{cannon}=m_{ball}{v}_{ball}+m_{cannon}{v}_{recoil}$

$⟹\left(1000\right)\left(5\right)=\left(5\right)\left(55\right)+\left(1000\right)\left(v\right)$

$⟹v=4.725m/s$ towards right