[填空题]
1.A ball of mass $0.20\,kg$ moving on a frictionless horizontal plane collides elastically with a vertical wall.
The variation of the force $F$ acting on the ball during the collision with time $t$ is shown on the graph below.
The speed of the ball just before the impact is $5.0\,m\,s^{-1}$. Calculate the maximum force exerted on the wall by the ball. $N$
2.The wall is covered with a coating that causes an inelastic collision. The ball hits the wall with the same initial speed and bounces back with a speed of $3.0\,m\,s^{-1}$.
1.Explain, by considering the moments just before and after the collision, how the principle of conservation of energy applies to the collision.
2.Calculate the loss of the energy $J$ of the ball during the collision.
3.During this collision, the ball undergoes a change in momentum. the the law of conservation of momentum in this situation.