有物理好的能帮下吗A 4.20 kg steel ball strikes a wall with a speed of

有物理好的能帮下吗
A 4.20 kg steel ball strikes a wall with a speed of 9.0 m/s at an angle of 60.0° with the surface.It bounces off with the same speed and angle.If the ball is in contact with the wall for 0.200 s,what is the average force exerted by the wall on the ball?(Assume right is the positive direction.)
1 N