Impulse and work for the bullet-block Veritasium video

摘要

In the January issue, Shakur uses conservation of linear momentum to explain why a uniform wooden block of mass M sitting on a stand and impacted by a bullet of mass m from below will rise to the same height regardless of whether the block is hit on or off center. He goes on to show that the fraction of the initial mechanical energy of the bullet that is converted into mechanical energy of the system after the bullet is embedded is about three times larger for the block hit off center than for the one hit on center. To gain further insight into what is happening, it is helpful to consider the force and torque exerted by the bullet on the block and how those relate to work and impulse.