Answer:
1) True: Spring A is stiffer than B (kA > kB). Less work must be expended on spring A if both springs are stretched by the same amount.
2) False: The kinetic energy of an object depends on the direction of the motion involved.
3) True: The work done to raise a box onto a platform does not depend on how fast it is raised.
4) True: The friction force is a non-conservative force.
5) True: The kinetic energy can be negative.
6) False: The kinetic energy does not depend on the reference frame of the observer.
7) False: Work can be done in the absence of motion.
8) False: If the moon revolves around the earth in a perfectly circular orbit, then the earth does do work on the moon.
