Author Question: Negative work can be done a. by friction on the tires while a car is accelerating without skidding. ... (Read 40 times)

nelaaney · **on:** Jul 28, 2018

Negative work can be done
a. by friction on the tires while a car is accelerating without skidding.
b. by a spring at the bottom of an elevator shaft when it stops a falling elevator.
c. by a hand catching a ball.
d. by all of the above. e. only by (b) and (c) above.

Question 2

Sally, who weighs 450 N, stands on a skate board while Roger pushes it forward 13.0 m at constant velocity on a level straight street. He applies a constant 100 N force.
a. The work Roger does on the skateboard is 0 J.
b. The work Roger does on the skateboard is 1 300 J.
c. The work Sally does on the skateboard is 1 300 J.
d. The work Sally does on the skateboard is 5 850 J.
e. The work Roger does on the skateboard is 5 850 J.