Question

A revolutionary war cannon, with a mass of
2090 kg, fires a 22.6 kg ball horizontally. The
cannonball has a speed of 137 m/s after it has
left the barrel. The cannon carriage is on a
flat platform and is free to roll horizontally.
What is the speed of the cannon immediately after it was fired?
this answer is 1.48m/s
The same explosive charge is used, so the total
energy of the cannon plus cannonball system
remains the same.
Disregarding friction, how much faster
would the ball travel if the cannon were
mounted rigidly and all other parameters remained the same?
Answer in units of m/s

Answer 1

Mounted rigidly means the cannon is not free to roll horizontally.

Answer 2

is that 137.73m/s?