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物体的运动速度发生了变化,其动量必定改变。物体动量的改变是由于物体受到了外力的冲量F△t。在物体作抛体运动时,其速度不断地改变,其动量也在不断地变化。当然,其动量变化的原因也是受到外力的冲量,因此,有可能用冲量和动量改变的关系即动量定理来解答抛体运动的问题。又由于作抛体运动的物体只受到一个重力的作用,而且方向竖直向下,所以物体受到的冲量大小即为mg△t,方向永远竖直向下。正是这种情况,给我们用动量定理来解答抛体
The speed of the object changes, and its momentum must change. The change in the momentum of an object is due to the fact that the object has been subjected to an external impulse FΔt. When an object moves as a body, its speed changes constantly, and its momentum changes constantly. Of course, the reason for the momentum change is also the impulse of the external force. Therefore, it is possible to use the momentum theorem to change the relationship between impulse and momentum to solve the problem of projectile motion. Because the object that is used as the body of the projectile is only subjected to a gravitational force and the direction is vertical downwards, the impulse size of the object is mg△t, and the direction is always vertical and downward. In this case, we use the momentum theorem to solve the projectile.