Physics Homework Problem?

Question

A 1.80-m tall person lifts a 2.30-kg book from the ground so it is 2.30 m above the ground.

 

 

1. What is the potential energy of the book relative to the ground?

 

 

2. What is the potential energy of the book relative to the top of the person's head?

 

 

3. How is the work done by the person related to the answers in parts A and B?

How is the work done by the person related to the answers in parts A and B?

	The work done by the person in lifting the book from the ground to the final height is the same as the answer to part A
	The work done by the person in lifting the book from the ground to the final height is the same as the answer to part B

 

Answer 1

1)

Mass of the book is  kg.

Height of the person is  m.

Height of the book  above the ground is  m.

Potential energy of the object is .

Where mass of the object and height of the object.

Find the potential energy of the book relative to the ground.

Substitute ,  and  in .

Potential energy of the book relative to the ground is 51.84 J.

Answer 2

2)

Find the potential energy of the book relative to the top of the persons head.

Whenever calculating potential energy relative to the top of the persons head, consider the height of the object above the persons head.

Height of the object above the persons head is  m.

Substitute ,  and  in .

Potential energy relative to the top of the persons head is 11.27 J.

Answer 3

3)

The work done by the person in lifting the book from the ground to the final height is the same as the answer to part (A).

In part (A), the potential energy is calculated relative to the starting location of the application of the force on the book.

The work done by the person is not related to the answer to part (B).

Option (A) is the correct choice.