7 circular Motion & Oscillations

How many radians are there is 360 degrees?

2 pi

What are the SI units of angular velocity?

Radians per second.

What is the definition of angular velocity?

The rate of change of angle.

How do you calculate angular velocity from time period (T)?

Angular velocity = 2 pi / T

How do you calculate angular velocity from frequency (f)?

Angular velocity = 2 pi f

What is required for uniform circular motion?

A force that always acts perpendicular to velocity.

Why doesn't a centripetal force do any work on an object in circular motion!

The force has no component in the dircetion of motion/is always perpendicular to motion.

How do you calculate linear velocity from the time period (T) of an object in circular motion?

v = 2 pi r / T

How do you calculate linear velocity from angular velocity?

v = angular velocity x radius

How is it possible for an object to experience an acceleration but travel at a constant speed?

If acceleration is perpendicular to velocity, the velocity will change direction whilst speed is constant.

What provides the centripetal force for a car turning a corner?

Friction from the road on the tyres.

What provides the centripetal force on the moon?

The gravitational attraction of the Earth.

Apart from friction what contributes to the centripetal force on a banked track?

The horizontal component of the normal reaction.

If a mass on a string is swung in a vertical circle where is the tension greatest?

At the bottom of the circle.

If a mass on a string is swung in a vertical circle where is the tension least?

At the top of the circle.

What is the equilibrium position in an oscillation?

The point at which an object experiences no resultant force and thus no acceleration (the 'rest' position of an object).

How many radians of phase are there in one complete oscillation?

2 x pi

How do you calculate the angular frequency of an oscillation?

2 x pi x the frequency of the oscillation

What are the conditions required for SHM?

The acceleration of an object is proportional, to its displacement from equilibrium and always in the opposite direction.

What is the acceleration of an object undergoing SHM when it's displacement is zero?

Zero

What is an Isochronous oscillator?

An oscillator with a period/frequency that is not dependent on amplitude.

What is a fiducial marker?

A pin or pointer placed at the equilibrium position of an oscillation.

What measures can be taken to improve the accuracy when measuring the time period of SHM?

Time over multiple oscillations and calculate the average of several repeats.

What is the kinetic energy of an SHM oscillator at maximum displacement?

Zero

How does the total energy in an SHM oscillator vary with time?

It is constant.

At what displacement is the potential energy of an SHM oscillator at a maximum?

At maximum displacement (x=±A).

How do you calculate the total energy of an SHM oscillator from its amplitude?

E = ½ k A²

What is a free oscillation?

An oscillation in which no external driving force is present

What causes damping of an oscillation?

An external force opposing motion.

What effect does damping of an oscillation have in terms of energy?

It transfers the KE of the oscillation to other forms, usually thermal energy.

What is light damping of an oscillation?

A small damping force causing the amplitude of the oscillations to decrease slowly.

What is heavy damping of an oscillation?

A damping force that results in a rapid decrease in the amplitude of oscillations.

What is very heavy damping of an oscillation?

A large damping force that prevents any oscillations of the system when its displaced.

What is the natural frequency of an oscillator?

The frequency at which osicllation will occur in a system with no external driving forces (free oscillations)

What is a forced oscillation?

An oscillation in which a (periodic) external driving force is present

What is a driving frequency in oscillations?

The frequency of the external driving force in a forced oscillation

What is resonance?

When the driving frequency of a forced oscillation is close to the natural frequency of the system resulting in large amplitude oscillations.

What is likely to occur when a mechanical system with little or no damping resonates?

The amplitude of the oscillations will increase until the object breaks.

What occurs in terms of energy during resonance?

There is the greatest possible transfer of energy from the driver to the forced oscillation.

What effects does increasing damping have on resonance?

It reduces the maximum amplitude and it reduces the frequency of maximum amplitude.