# Inelastic collision of a cannonball

1. Mar 8, 2016

### reminiscent

1. The problem statement, all variables and given/known data

2. Relevant equations
Total initial momentum = total final momentum
Momentum = m*v
Kinetic energy = 1/2 * m * v2

3. The attempt at a solution
What I found so far:
m1v1i = (m1+m2)vf
Total kinetic energy = 1/2 * (m1 + m2)vf2 - 1/2 * m1 * v1i2

I am confused on how friction comes into play here. I know that friction is a non-conservative force.

2. Mar 9, 2016

### ehild

You can take the whole process as two stages.
The cannonball hits the tank, and is embedded. What kind of collision is this? Is energy conserved?
After the collision, the tank and the ball inside, move on a rough pavement and come to rest at 50 cm distance. What kind of motion is that?

3. Mar 9, 2016

### SteamKing

Staff Emeritus
The energy imparted to the tank by the projectile must be used to move the tank against the friction which exists between the tank and the pavement. In essence, part of the energy of the projectile must be converted to work in order to overcome friction.

4. Mar 9, 2016

### reminiscent

So since this is an elastic collision, momentum is conserved but KE is not. I would have to substitute what I found first into Kf, then that would equal to mu*(total mass)*g*d, correct? I just solve for v initial for the cannon ball. I got 377 m/s.

5. Mar 9, 2016

### ehild

The result is correct.