Unit 1 RMA

Question 1

What is velocity?

Answer 1

Velocity is the rate of change of displacement with time.

Question 2

What is acceleration?

Answer 2

Acceleration is the rate of change of velocity with time and the second differential of displacement with time.

Question 3

Gradient of a curve (or line)

Answer 3

The gradient of a curve (or line) represents instantaneous rate of change and can be found by differentiation.

Question 4

Area under a curve (or line)

Answer 4

The area under a curve (or line) can be found by integration.

Question 5

What is angular velocity?

Answer 5

Angular velocity is the rate of change of angular displacement.

Question 6

What is angular acceleration?

Answer 6

Angular acceleration is the rate of change of angular velocity.

Question 7

How is circular motion maintained?

Answer 7

A centripetal (radial or central) force acting on an object is necessary to maintain circular motion, and results in centripetal (radial or central) acceleration of the object.

Question 8

What is torque?

Answer 8

Torque is the turning effect of a force. It is also called the moment of a force.

Question 9

What does an unbalanced torque cause?

Answer 9

An unbalanced torque causes a change in the angular (rotational) motion of an object.

Question 10

What is moment of inertia?

Answer 10

The moment of inertia of an object is a measure of its resistance to angular acceleration about a given axis.

Question 11

What does moment of inertia depend on?

Answer 11

Moment of inertia depends on mass and the distribution of mass about a given axis of rotation.

Question 12

Conservation of angular momentum

Answer 12

The total angular momentum before an impact will equal the total angular momentum after impact providing no external torques are acting.

Question 13

What is gravitational field strength?

Answer 13

Gravitational field strength is the gravitational force acting on a unit mass.

Question 14

What is gravitational potential?

Answer 14

The gravitational potential of a point in space is the work done in moving a unit mass from infinity to that point.

Question 15

What is an AU?

Answer 15

One astronomical unit (AU) is the average distance between Earth and the Sun.

Question 16

Does the energy required to move mass between two points in a gravitational field depend on the path taken?

Answer 16

The energy required to move mass between two points in a gravitational field is independent of the path taken.

Question 17

What is escape velocity?

Answer 17

The minimum velocity required to allow a mass to escape a gravitational field to infinity, where the mass achieves zero kinetic energy and maximum (zero) potential energy.

Question 18

What is a light year?

Answer 18

The distance travelled by light in one year.

Question 19

What do equipotential lines do?

Answer 19

Equipotential lines join points of equal gravitational potential. They are always at right angles to field lines.

Question 20

What is the difference between special relativity and general relativity?

Answer 20

Special relativity deals with motion in inertial (non-accelerating) frames of reference, whereas general relativity deals with motion in non-inertial (accelerating) frames of reference.

Question 21

What is the equivalence principle?

Answer 21

It is not possible to distinguish between the effects on an observer of a uniform gravitational field and of a constant acceleration.

Question 22

What is spacetime?

Answer 22

It is a unifies representation of three dimensions of space and one dimension of time.

Question 23

What does general relativity lead to?

Answer 23

General relativity leads to the interpretation that mass curves spacetime, and that gravity arises from the curvature of space time.

Question 24

What path does light follow in spacetime?

Answer 24

Light or a freely moving object follows a geodesic (the path with the shortest distance between two points) in spacetime.

Question 25

What is escape velocity from the event horizon of a black hole?

Answer 25

Escape velocity from the event horizon of a black hole is equal to the speed of light.

Question 26

Time appears frozen at the event horizon of a black hole

Answer 26

From the perspective of a distant observer, time appears to be frozen at the event horizon of a black hole.

Question 27

What is the Schwarzschild radius of a black hole?

Answer 27

The Schwarzschild radius of a black hole is the distance from its centre (singularity) to its event horizon.

Question 28

What are lines drawn on spacetime diagrams called?

Answer 28

Lines drawn on spacetime diagrams are called worldlines.

Question 29

How is a black hole formed?

Answer 29

A black hole is formed when a massive star runs out of fuel for fusion and collapses in on itself.

Question 30

How are stars formed?

Answer 30

Stars are formed in interstellar clouds when gravitational forces overcome thermal pressure, and cause a molecular cloud to contract until the core becomes hot enough to sustain nuclear fusion, which then provides a thermal pressure that balances the gravitational force.

Question 31

What is the first stage in a proton-proton chain?

Answer 31

Two protons fuse together to produce a deuterium, a positron, and a neutrino.

Question 32

What is the third stage in a proton-proton chain?

Answer 32

The combination of two Helium-3 nuclei results in the final step producing Helium-4

Question 33

What is the second stage in a proton-proton chain?

Answer 33

The deuterium fuses with another proton to give Helium-3. A gamma ray is released at the same time.