Simple Harmonic Motion (Module 18)

Question 1

Define free vibrations.

Answer 1

If the amplitude is constant and no frictional forces are present, the oscillations are therefore describes as free vibrations.

Question 2

How do you calculate phase difference in radians?

Answer 2

Phase difference = (2 x pi x change in time) / T

Question 3

Define simple harmonic motion.

Answer 3

This is an oscillating motion in which the acceleration is proportional to the displacement and always in the opposite direction to the displacement ( a is proportional to - displacement).

Question 4

Define the term Damping.

Answer 4

Damping is when the oscillations of a simple pendulum gradually die away because air resistance (or another force) gradually reduces the total energy of the system.

Question 5

What is the difference between light, critical and heavy damping?

Answer 5

Light damping is when the amplitude gradually decreases with time by the same fraction each cycle. Heavy damping is when the amplitude has no oscillating motion but decreases at a faster rate to light damping. Critical damping has no oscillating motion and as soon as released returns to equilibrium in the shortest possible time.

Question 6

Define periodic force.

Answer 6

This is when a force is applied at regular intervals (for example, a swing with suitability timed pushes)

Question 7

How do you get a system at resonance?

Answer 7

The applied frequency of the periodic force must equal the natural frequency of the system.

Question 8

Define resonant frequency.

Answer 8

The frequency at the maximum amplitude is called the resonant frequency.