Question

(A)How much work does it take to lift a 1.4kg physics book from the floor to a desk that is 70cm high?(B) if the same physics book is then put on a shelf that is 2.1m high what is the book’s potential energy?

Answer 1

Answer: A. Work = 9.6 J

B. PE= 29 J

Explanation: To find work use the formula:

W= Fxd

Convert first 70 cm to m

70 cm x 1m/ 100 cm= 0.7m

W= F x d

= 1.4 kg (9.8m/s²) ( 0.7m)

= 9.6 J

To solve for the Potential Energy use the following formula:

PE= mgh

= 1.4 kg ( 9.8 m/s²) ( 2.1m)

= 29 J