Negative work can be done a. by friction on the tires while a ...

[nelaaney]

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.

[aliotak]

Answer to Question 1

E

Answer to Question 2

B

[nelaaney]

Gracias!

[dyrone]

Excellent