1. The problem statement, all variables and given/known data A truck speeding down the highway has a lot of kinetic energy relative to a stopped state trooper, but no kinetic energy relative to the truck driver. In these two frames of reference, is the same amount of work required to stop the truck? Explain. 2. Relevant equations 3. The attempt at a solution I thought like this: a) If we are looking from outside, truck has the velocity V and the environment has none. Thus dK=W necessary to stop the truck would be equal to K.E of the truck. b) On the other hand, if we are the driver, the environment has the velocity V and we have none. Thus again W=dK necessary to stop the 'environment' would be equal to the K.E of the truck in part a. I think it is logical, and all I ask from you is to tell me if the explanation makes sense to you? Is it clear? Does it involve any contradictions or any sign errors?