Chapter 17.1, Problem 3cTH

Consider reference frame R, moving downward with constant speed ${\upsilon }_o$ .

i. In the spaces provided, draw arrows to indicate the direction of the velocity and the acceleration of the block in reference frame R during the interval $△t_o$ Explain.
ii. In reference frame R:
• is the block speeding up, slowing down, or moving with constant speed? (Base your answer on the directions of the velocity and acceleration).
• is the change in kinetic energy of the block positive, negative, or zero? Explain.
iii. The work-energy theorem can be applied in any inertial frame of reference. Apply the theorem to determine whether the net work done on the block is positive, negative, or zero in reference frame R. Explain.
iv. In reference frame R, during the interval $△t_o$ :
• is the displacement (i.e., change in position) of the block upward, downward, or zero? Explain. (Base your answer on your velocity arrow in part c.i.)
• is the net force on the block upward, downward, or zero? Explain. (Base your answer on your acceleration arrow in part c.i.)
• is the work done on the block by the net force positive, negative, or zero? Explain. (Base your answer on your answers to the previous two questions.)
Make sure your result for the work done on the block by the net force is consistent with your answer to part c.iii.