Unit 1 RMA Flashcards
What is velocity?
Velocity is the rate of change of displacement with time.
What is acceleration?
Acceleration is the rate of change of velocity with time and the second differential of displacement with time.
Gradient of a curve (or line)
The gradient of a curve (or line) represents instantaneous rate of change and can be found by differentiation.
Area under a curve (or line)
The area under a curve (or line) can be found by integration.
What is angular velocity?
Angular velocity is the rate of change of angular displacement.
What is angular acceleration?
Angular acceleration is the rate of change of angular velocity.
How is circular motion maintained?
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.
What is torque?
Torque is the turning effect of a force. It is also called the moment of a force.
What does an unbalanced torque cause?
An unbalanced torque causes a change in the angular (rotational) motion of an object.
What is moment of inertia?
The moment of inertia of an object is a measure of its resistance to angular acceleration about a given axis.
What does moment of inertia depend on?
Moment of inertia depends on mass and the distribution of mass about a given axis of rotation.
Conservation of angular momentum
The total angular momentum before an impact will equal the total angular momentum after impact providing no external torques are acting.
What is gravitational field strength?
Gravitational field strength is the gravitational force acting on a unit mass.
What is gravitational potential?
The gravitational potential of a point in space is the work done in moving a unit mass from infinity to that point.
What is an AU?
One astronomical unit (AU) is the average distance between Earth and the Sun.
Does the energy required to move mass between two points in a gravitational field depend on the path taken?
The energy required to move mass between two points in a gravitational field is independent of the path taken.
What is escape velocity?
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.
What is a light year?
The distance travelled by light in one year.
What do equipotential lines do?
Equipotential lines join points of equal gravitational potential. They are always at right angles to field lines.
What is the difference between special relativity and general relativity?
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.
What is the equivalence principle?
It is not possible to distinguish between the effects on an observer of a uniform gravitational field and of a constant acceleration.
What is spacetime?
It is a unifies representation of three dimensions of space and one dimension of time.
What does general relativity lead to?
General relativity leads to the interpretation that mass curves spacetime, and that gravity arises from the curvature of space time.
What path does light follow in spacetime?
Light or a freely moving object follows a geodesic (the path with the shortest distance between two points) in spacetime.
What is escape velocity from the event horizon of a black hole?
Escape velocity from the event horizon of a black hole is equal to the speed of light.
Time appears frozen at the event horizon of a black hole
From the perspective of a distant observer, time appears to be frozen at the event horizon of a black hole.
What is the Schwarzschild radius of a black hole?
The Schwarzschild radius of a black hole is the distance from its centre (singularity) to its event horizon.
What are lines drawn on spacetime diagrams called?
Lines drawn on spacetime diagrams are called worldlines.
How is a black hole formed?
A black hole is formed when a massive star runs out of fuel for fusion and collapses in on itself.
How are stars formed?
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.
What is the first stage in a proton-proton chain?
Two protons fuse together to produce a deuterium, a positron, and a neutrino.
What is the third stage in a proton-proton chain?
The combination of two Helium-3 nuclei results in the final step producing Helium-4
What is the second stage in a proton-proton chain?
The deuterium fuses with another proton to give Helium-3. A gamma ray is released at the same time.
