A cannon that is 10m long is designed to launch a 10kg ball over a castle wall.
In order to do this the ball must have a speed of at least 50m/s as it exits the
cannon. For every 10kg of explosives used, the force on the ball in the cannon
increases by 1000N. How many kg of explosives should they use?
F=1000n,
F=ma,
a=F/m=1000n/10= 100n.
a=v²/2s,
v²/2s=100n,
n= v²/200s=50²/200•10=1.25.
The amount of explosive is
1.25•10 =12.5 kg.