# Work on object lifted in a gravational field

• sracks
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.

#### sracks

A 1.1 kg book is lying on a 0.80-m-high table. You pick it up and place it on a bookshelf 2.17 m above the floor.

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

The book is initially on the table and then its moved to the shelf. So it moved (2.17-0.8) m
Also, work done by gravity will be negative.

Help

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$$\Delta$$r

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

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! )

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

I have a feeling that i am completely doing it wrong

Got it

## What is work?

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.

## What is an object lifted in a gravitational field?

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.

## How does gravitational potential energy relate to work?

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.

## What is the formula for calculating work done on an object lifted in a gravitational field?

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.

## How does the weight of an object affect the work done when it is lifted in a gravitational field?

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.