Truck Collision

Discussion of the questions

问题讨论

在正面碰撞中：哪一辆卡车会受到最大的力？哪一辆卡车会受到最大的冲量？哪一辆卡车会受到最大的动量变化？哪一辆卡车会受到最大的速度变化？哪一辆卡车会受到最大的加速度？在碰撞中，你更希望在哪一辆卡车里？

Truck Collision

Comparison of the collision variables for the two trucks:

In a head-on collision: Newton's third law dictates that the forces on the trucks are equal but opposite in direction. Impulse is force multiplied by time, and time of contact is the same for both, so the impulse is the same in magnitude for the two trucks. Change in momentum is equal to impulse, so changes in momenta are equal. With equal change in momentum and smaller mass, the change in velocity is larger for the smaller truck. Since acceleration is change in velocity over change in time, the acceleration is greater for the smaller truck. 在正面碰撞中：牛顿第三定律指出，卡车上的力大小相等但方向相反。冲量是力乘以时间，接触时间对两者而言相同，因此两辆卡车的冲量大小相等。动量的变化等于冲量，因此两辆卡车的动量变化相等。由于动量变化相等而小卡车质量更小，因此小卡车的速度变化更大。由于加速度是速度变化除以时间变化，因此小卡车的加速度更大。

Ride in the bigger truck! There are good physical reasons!

Collision questions

碰撞问题

Truck Collision

Even though the forces are equal in magnitude on the two trucks, the smaller truck experiences the greater acceleration. 尽管两辆卡车上的力大小相等，但较小的卡车所受的加速度更大。

The change in velocity of the driver will be the same as the truck in which he/she is riding. A greater change in velocity implies a greater change in kinetic energy and therefore more work done on the driver. 驾驶员的速度变化将与他/她所乘坐的卡车相同。速度的变化越大，动能的变化也越大，因此对驾驶员做的功也越多。 在正面碰撞中，根据牛顿第三定律，两辆车上的力被约束为相同。但根据牛顿第二定律和功-能原理，显然在较大的卡车里更安全。