Gravitational Fields

Question 1

Newton’s Law Of Universal Gravitation

Answer 1

Newton’s Law Of Universal Gravitation states that every particle in the Universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between the centres

Question 2

Gravitational field strength

Answer 2

Gravitational field strength is the force acting on a unit mass of 1kg inside the field.

Question 3

Gravitational potential

Answer 3

Gravitational potential at a point in a gravitational field is the work done in bringing a unit mass from infinity to that point.
The gravitational potential at an infinite distance is zero

Question 4

Escape velocity

Answer 4

The minimum speed with which a mass should be projected from the Earth’s surface in order to escape Earth’s gravitation field ignoring air resistance.

Question 5

Why is gravitational potential energy negative?

Answer 5

Gravitational potential energy is the work done in bringing a unit mass from infinity to that point. Potential energy at infinity is zero. Work done is by the field so all points closer than infinity is negative.