Particle Newtonian Mechanics - Conceptual Example 5.1-3

 

An astronaut floating weightlessly in space shakes a wrench in his hand back and forth. Which of the following is true.

 

The shaking requires no effort because the wrench has no inertia to resist the motion.
The shaking requires some effort, but less than on earth because the wrench weighs less in space.
The shaking requires the same amount of effort as on earth because the inertial mass of the wrench is the same no matter the wrench's location.