1. Gravitational Fields, Gravitational Potential Energy & Gravitational Potential

2. Gravitational Fields
It is often useful to relate the Force experienced to a specific location.
For instance, a 30 kg person would experience 294 N of Force. A 70 kg person would experience 686 N of force.
F = mg
We could say that at this particular spot, the Gravitational Field Strength is 9.8 N/kg
What force would a 95 kg person experience at this location?
Is it valid for other locations?

3. Electric and Gravitational Fields
Similarly, we could define an Electric Field as the electric force per unit charge at a specific location
Gravitational Fields
Electric Fields
Exists in the space surround an object in which the force of gravity exists
A field illustrating the force of attraction between two objects
The region in which a force is exerted on an electric charge by another electrical source

4. Gravitational Fields
Gravitational Fields
Depending on our location on the earth we experience a different gravitational field strength
We approximately 9.8 N/kg

5. Gravitational Potential Energy
Potential Energy is the stored energy of position of an object an it is related to the location of the object within a field.
Gravitational Potential Energy (GPE) – the stored energy due to attractive forces of large masses and their relative distances.

6. Potential Energy Gravitational Potential Energy
When gravity does work on an object, it GPE is lowered.
High GPE
GPE  KE
Lower GPE

7. Gravitational Potential
1 kg
GPE depends on the mass of an object and its height.
An object with twice the mass will have twice the potential energy and an object with twice the distance will have twice the potential energy.
An object an a high position does not necessarily mean high potential energy and low positions don’t mean low potential energy
The GPE for both balls is 20 J
2 kg
2 m
1 m

8. Gravitational Potential
Gravitational Potential Energy depends on mass and height
Gravitational Potential tells us the amount of potential energy per kilogram at a particular spot.
Gravitational Potential
20J/kg
10J/kg
0 J/kg
1 kg, 2m
20J GPE
2 kg, 2m
40J GPE
1 kg, 1m
10J GPE
2 kg, 1m
20J GPE