Physics
posted by Sam .
A 3.6 kg ball strikes a wall with a velocity of 9.3 m/s. The ball bounces off with a velocity of 7.9 m/s in the opposite direction. If the ball is in contact with the wall for 0.4 seconds, what is the constant force exerted on the ball by the wall?

force*time=mass(changeinvelocity)
= mass(VfVi)
= mass(7.9+9.3)
solve now for force.
Notice the sign change in velocity, that is what OPPOSITE direction is, a sign change.