Advanced Higher Physics: Uni1 1

Rotational Motion and Astrophysics

Gravitational Field Strength

The gravitational force per unit mass

Gravitational Potential

The work done in moving unit mass from infinity to that point to a point in the gravitational field

angular velocity

Rate of change of angular displacement

Escape velocity

the minimum velocity needed to escape a gravitational field

Schwarzschild Radius

The distance from the centre to the event horizon in any black hole

geodesic

The shortest distance between two points

Centripetal Force

The unbalanced force that is required to keep an object moving in a circle with a constant tangential speed.

Torque

The force that produces a turning effect on an object

Unbalanced torque

Produces an angular acceleration about an axis of rotation

Inertial frame

A frame of reference that is stationary or moving at a constant speed

Non-inertial frame

A frame of reference that is accelerating

Decelerating wordline

Accelerating wordline

Stationary wordline

Moving at constant speed

Conservation of angular momentum

Total angular momentum before an event = total angular momentum after an event in the absence of external torques

Black hole

A region of spacetime with a strong gravitational field so that the escape velocity is grater than the speed of light

Gravitational Lensing

A distribution of matter, between a distant light source and an observer, causing a bending of the light from the source as the light travels towards the observer

Equivalence principle

It is impossible to tell the difference between the effects of gravity and moving at a constant acceleration