Chapter 13. Gravitational Fields

Question 1

Define gravitational field

Answer 1

A gravitational field is a region of space where a mass experiences a force.

Question 2

Define gravitational field strength

Answer 2

The gravitational field strength at a point is defined as the force per unit mass
acting on a small mass placed at that point.

Question 3

Define gravitational field lines

Answer 3

A gravitational field line is the direction of the gravitational force acting on a
point mass.

Question 4

What is newton’s law of gravitation

Answer 4

Newton’s law of gravitation states that two point masses attract each other with a
force that is proportional to the product of their masses and inversely proportional
to the square of their separation.

Question 5

Define gravitational potential

Answer 5

Gravitational potential at a point in a gravitational field is defined as the work
done per unit mass in bringing a small test mass from infinity to the point.

Question 6

Why is gravitational potential negative?

Answer 6

The gravitational potential at infinity is defined as being zero. The gravitational force is always attractive and so, as the test mass moves from infinity, work can be done by the test mass and as a result its potential decreases. The gravitational potential is negative.