Gravitation

Question 1

Newton’s Universal Law of Gravitation

Answer 1

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The force of gravity between two objects is directly proportional to the product of the two masses and inversely proportional to the square of the distance between them and acts along a line joining at their centres
(Note: the objects are point masses. If not point masses but very far apart (distance between then>than their radii, can be treated like point masses)

Question 2

Gravitational Field Strength

Answer 2

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(g)
Gravitational force per unit mass on a point mass (g=Fg/m)

Question 3

Kepler’s Third Law

Answer 3

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Ratio of orbital period squared to average orbital radius cubed is constant for all planets

Question 4

Weightlessness in orbital motion

Answer 4

A sensation of weightlessness due to the spacecraft and all objects in it being constant free-fall together as they circle Earth

Question 5

Weightlessness in free-fall

Answer 5

A sensation of weightlessness because a person is falling freely towards the Earth, hence there is no normal force acting on the person due to gravity

Question 6

Weightlessness in deep space

Answer 6

A sensation of weightlessness due to the minimal pull of gravity very far from any massive object