Astrophysics Definitions

Question 1

Gravitational Field Strength

Answer 1

The gravitational force per unit mass ( weight per unit mass)

Question 2

Gravitational potential of a point in Space

Answer 2

The work done in moving unit mass from infinity to that point.
( Energy to move 1kg of mass from infinity to that point in space your refering to)

Question 3

Escape Velocity

Answer 3

The minimum velocity required by a mass to just escape from a planet’s gravitational field and reach infinity with zero velocity or zero kinetic energy.

Question 4

Inertial frame of reference

Answer 4

A frame of reference in which an observer is not accelerating with respect to another.
That is, an observer will move at a constant speed with respect to another.

Question 5

Non-Inertial Frame of Reference

Answer 5

A frame of reference in which an observer is accelerating with respect to another.
That is, an observer will not move at a constant speed with respect to another. (General Relativity)

Question 6

Equivalence Principle

Answer 6

Gravity Pulling in one direction is equivalent to acceleration in the other.
That is, there is no way to distinguish between the effects on an observer of a uniform gravitational fields and of a constant acceleration.

Question 7

Spacetime

Answer 7

A unified representation of three dimension of space and one dimension of time.

Question 8

Gravitational Lensing

Answer 8

The Bending of light from a distant source due to a large mass causing a curvature in Spacetime.

Question 9

Schwarzschild Radius

Answer 9

The distance from the centre of a black hole (i.e. the singularity) to its event horizon.