- #1

- 9

- 0

How much work does gravity do on the book?

How much work does your hand do on the book?

W=mgh

(1.1 kg)(9.8 m/s^2)(0.8m)=8.6

The answers that I am getting are wrong

Please help

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In summary, the book initially has a mass of 1.1 kg and is moved from a table at a height of 0.8 m to a bookshelf at a height of 2.17 m. The work done by gravity on the book is calculated to be 8.6 Joules. The work done by the hand on the book is not calculated. In the second problem, a 10 g particle initially moving to the left at 29 m/s is required to be moved to the right at 47 m/s. The net work needed to achieve this is calculated to be 1.7 Joules.

- #1

- 9

- 0

How much work does gravity do on the book?

How much work does your hand do on the book?

W=mgh

(1.1 kg)(9.8 m/s^2)(0.8m)=8.6

The answers that I am getting are wrong

Please help

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- #2

- 85

- 0

Also, work done by gravity will be negative.

- #3

- 9

- 0

Now I have another problem

A 10 g particle is moving to the left at 29 m/s. How much net work must be done on the particle to cause it to move to the right at 47 m/s?

W=mg[tex]\Delta[/tex]r

I got 1.7. I don't think I am doing this right.

- #4

Science Advisor

Homework Helper

- 25,839

- 257

sracks said:I got 1.7. I don't think I am doing this right.

Show us how you got 1.7

(btw, if you type alt-j, it give you ∆ without having to tex! )

- #5

- 9

- 0

(.01kg)(9.8m/s^2)(47 m/s - 29m/s) = 1.7

I have a feeling that i am completely doing it wrong

I have a feeling that i am completely doing it wrong

- #6

- 9

- 0

Forget about this question. I got it

Work is a measure of the energy transferred to or from an object by a force when it is displaced in the direction of that force.

An object lifted in a gravitational field is any object that is being moved against the force of gravity, such as lifting a book off the ground or raising a weight on a pulley.

Gravitational potential energy is the energy an object has due to its position in a gravitational field. When an object is lifted in a gravitational field, work is done against the force of gravity and the object gains gravitational potential energy.

The formula for calculating work done on an object lifted in a gravitational field is W = mgh, where m is the mass of the object, g is the acceleration due to gravity, and h is the height the object is lifted.

The weight of an object affects the work done when it is lifted in a gravitational field because work is directly proportional to the force applied and the distance over which it is applied. Therefore, the greater the weight of the object, the more work is required to lift it to a certain height against the force of gravity.

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