Gravitation

Question 1

Pressure

Answer 1

The normal force acting per unit cross sectional area.

Question 2

Archimedes principle

Answer 2

A body partially or completely immersed in a fluid experiences a buoyant force that is equal to the weight of the displaced fluid.

Question 3

What is a gravitational field?

Answer 3

A volume of space where a mass experiences a force.

Question 4

Gravitational field strength

Answer 4

The gravitational force exerted per unit mass on a test mass placed at that point in the field.

Question 5

What is a radian?

Answer 5

One radian is the angle subtended at the centre of a circle by an arc of length equal to the radius of that circle.

Question 6

Kepler’s First Law

Answer 6

All the planets move in elliptical orbits with the sun at one focus of the ellipse.

Question 7

Kepler’s Second Law

Answer 7

A line from the sun to a planet will sweep out equal areas in equal times as the planet moves in its orbit.

Question 8

Kepler’s Third Law (in words)

Answer 8

The square of the period of the orbit is proportional to the cube of the semi-major axis.

Question 9

Newton’s Law of Gravitation (in words)

Answer 9

Any two point masses attract each other with a force that is directly proportional to the product of the two masses, and inversely proportional to the square of the distance between them.

Question 10

Gravitational Potential Energy (in words, and the one we use for radial fields)

Answer 10

The GPE at a point is equal to the work done in moving a test mass from infinity to that point in the gravitational field.

Question 11

Gravitational Potential

Answer 11

The gravitational potential at a point is the work done per unit mass in moving a test mass from infinity to that point in the gravitational field.