21.1 Gravitational Field strength

Question 1

Describe a radial field

Answer 1

• Field lines are always directed into the centre of the of the field
• Magnitude of g decreases the further from the centre of the radial field you go

Question 2

Describe a uniform field

Answer 2

• Gravitational field strength is the same in magnitude and direction in a field
• Field lines are therefore parallel and equally spaced

Question 3

What is meant by the strength of a gravitational field

Answer 3

The strength of the gravitational field (g), is the force per unit mass on a small test mass placed in a field

Question 4

How can the field around the earth be considered uniform?

Answer 4

The field around the earth is radial, however over small distances, and this means small distances in comparison to the radius of the earth, the field is uniform as the value for g does not change over this distance. On the surface of the earth, g is 9,81, and 100m above the surface, it is also 9.81.

Question 5

What is the unit for gravitational field strength?

Answer 5

NKg^(-1)