3.1 Uniform gravitational fields

Question 1

Where is the gravitational field of the earth uniform

Answer 1

Near the earth’s surface

Question 2

What is meant by a uniform gravitational field

Answer 2

Where the size of the gravitational force on an object in the field is the same in every place

Question 3

Describe the gravitational field on the earth’s surface

Answer 3

The lines of force are parallel and equally spaced, and the arrows point straight downwards into the earth

Question 4

What is the equation for gravitational field strength

Answer 4

g = F/m

Question 5

Define gravitational field

Answer 5

A region in which a mass experiences a force

Question 6

How do different objects accelerate if they are in the same gravitational field

Answer 6

In the same gravitational field, all objects fall with the same acceleration

Question 7

Define gravitational field strength

Answer 7

The gravitational force per unit mass acting on a mass at that point in a gravitational field

Question 8

Near the surface the earth’s field is uniform. This is an approximation. What shape is the earth’s field and what does this mean for the strength in relation to the height.

Answer 8

The earth’s field is radial so the strength of the field decreases with height

Question 9

What are reasons for the variation of g around the earth

Answer 9

The earth is not an exact sphere. Variation is also caused by the earth’s rotation

Question 10

What can geologists do locally using data and detections of tiny variations of g

Answer 10

They can use this to predict what is below the surface and this could help them to locate oil deposits and places where fracking is most likely to produce oil and gas

Question 11

Define equipotential surface

Answer 11

Any surface where there is no change in GPE of an object when it is moved from one place to another on this particular surface

Question 12

What is the amount of work needed to move an object across an equipotential surface

Answer 12

zero