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9.2 GRAVITATIONALPOTENTIAL (AHL)

When will the GPE on an object increase? What causes them to have GPE?

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9.2 GRAVITATIONALPOTENTIAL (AHL)

When will the GPE on anobject increase?

The higher you lift an object themore potential energy it has

because the more work you hadto do to put it there.

GPE = mgh What causes them to have

GPE? Objects in a gravitational field

have the potential to do work if

they have a force acting on

them.

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9.2 GRAVITATIONALPOTENTIAL (AHL)

GPE depends on: mass, m Where it is, gh.

The where it is is calledgravitational potential.

PE= mgh

PE

m= gh

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9.2 GRAVITATIONALPOTENTIAL (AHL)

GPE depends on: mass, m Where it is, gh.

The where it is is calledgravitational potential, V.

PE=mgh

PE

m= gh

V= gh

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QUESTIONS

What is the potential at A?

What is the change in potential if object moves fromA to B?

What is the potential difference between A and E?

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

height(m)

B

AE

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9.2 GRAVITATIONALPOTENTIAL (AHL)

Where will you have the maximum GPE? Where is the gravitational force between objects

zero?

What is the maximum value of GPE?

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9.2 GRAVITATIONALPOTENTIAL (AHL)

Where will you have the maximum GPE? Max height infinity distance

Where is the gravitational force between objectszero?

Gravitational law equation the more the distance(r) the less the force.. So at infinity distance

What is the maximum value of GPE? ZERO!!!! No force no potential energy

To infinity. and beyond

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9.2 GRAVITATIONALPOTENTIAL (AHL)

What will the GPE Buzz lightyear is returningfrom infinity to point p?

From infinity to point P

P

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9.2 GRAVITATIONALPOTENTIAL (AHL)

What will the GPE Buzz lightyear is returningfrom infinity to point p?

When you move back towards Earth frominfinity, your PE reduces. So it must become less

than zero! It must become negative.

Remember the dog and work example?

From infinity to point P

P

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9.2 GRAVITATIONALPOTENTIAL (AHL)

When you move back towards Earth frominfinity, your PE reduces. So it must become less

than zero! It must become negative.

Work was negative because your force is oppositeof the direction of movement.. Same thing here..U wont need to pull the object.. It will pull u..

From infinity to point P

P

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9.2 GRAVITATIONALPOTENTIAL (AHL)

Lets define gravitationalpotential:

Work done per unit mass taking asmall test mass from infinity to a

point. (as we say with Buzz goingback)

Gravitational potentialENERGY:

work done in moving mass frominfinity to a point

PE=mgh

PE

m= gh

V= gh

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9.2 GRAVITATIONALPOTENTIAL (AHL)

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9.2 GRAVITATIONALPOTENTIAL (AHL)

If we plot the gravitational force and distance..

Can you explain the graph and what informationcan we get?

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9.2 GRAVITATIONALPOTENTIAL (AHL)

W = Fs

W = "GMm

r

V =W

m= "

GM

r

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9.2 GRAVITATIONALPOTENTIAL (AHL)

The gradient of a graph of gravitational potentialagainst distance is..

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9.2 GRAVITATIONALPOTENTIAL (AHL)

The gradient of a graph of gravitational potentialagainst distance is.. g ?? Why negative? Theslope is positive but g is negative so we take the

negative of the gradient

g = "gradient= "#V

#x

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QUESTION

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QUESTION