Mechanics Flashcards
Explain what the moment of inertia depends on
The mass of the object and the distribution of mass about a fixed axis
Explain what is meant by the moment of a force.
The turning effect of a force on a rotating object
What does an object’s rotational kinetic energy depend on?
The moment of inertia and it’s angular velocity
Define gravitational field strength
The force per unit mass at a particular point in the objects gravitational field
Explain gravitational potential energy
The work done by external forces to move a unit mass from infinity to that point
Where is the zero of gravitational potential?
Infinity
Explain what a conservative field means.
The work done in moving a mass between two points in the field is independent of the path taken
Define ‘escape velocity’
Minimum velocity required to escape completely from the gravitational attraction of a planet and reach infinity with zero velocity
Are photons affected by gravitational fields?
Yes. Black holes have an escape velocity more than c and so even photons can’t escape from within a certain distance
Derive v = sqrt(2GMm/r)
For the escape velocity
Total energy will equal zero when at infinity with zero velocity and zero potential.
Ek + Ep = 0
Solve for velocity
Describe example of SHM
Simple pendulum
Guitar string
Tuning Fork
Mass on spring
Describe SHM
An object oscillates about an equilibrium position under the influence of an unbalanced force which is:
- proportional to objects displacement from equilibrium
- directed towards the equilibrium position
Explain significance of equation
d2y/dt2 = -w^2 y
An object moving in a unit circle with angular velocity w will display SHM for the displacement (y) from the x axis
y = radius * sine( angle )
= r * sin(w*t)
Then double differentiate to get
-w^2 * r * sin(w*t)
Substitute in y
D2y/Dt2 = -w^2*y
The DEFINITION for SHM
What does the term damping mean?
An energy loss from an oscillating system. The result is the AMPLITUDE DECAYS with time
Evidence for electromagnetic radiation wave-particle duality
Wave- interference patterns/ diffraction
Particle - photoelectric effect threshold frequency
