Chapter 7 Review Questions

A 10 lb weight is lifted 5 ft. A 20 lb weight is lifted 2.5 ft. Which lifting required the most work?

(a) 10 lb weight

(b) 20 lb weight

(c) same work for each lifting

(d) not enough information is given to work the problem

Two cars, A and B, travel as fast as they can to the top of a hill. If their masses are equal and they start at the same time, which one does the most work if A gets to the top first?

(a) A

(b) B

(c) they do the same amount of work

An object of mass 6 kg is traveling at a velocity of 30 m/s. How much total work was required to obtain this velocity starting from a position of rest?

(a) 180 Joules

(b) 2700 Joules

(c) 36 Joules

(d) 5 Joules

(e) 180 N

A 20 pound weight is lifted 4 feet. The change in potential energy of the weight in ft^.lb is

(a) 20

(b) 24

(c) 16

(d) 80

(e) 5