Vibrations

Question 1

What is meant by simple harmonic motion?

Answer 1

When the acceleration of a body is directly proportional to its distance from a fixed point and is always directed toward that point.

Question 2

When an object is oscillating, and is at the centre of its path, is velocity maximum or minimum?

Answer 2

Maximum

Question 3

When an object is oscillating, and is at the peak of its path (displacement is maximum), what is its acceleration?

Answer 3

Maximum but in the opposite direction

Question 4

Describe the energy transfer in an oscillating system

Answer 4

Energy is transferred between kinetic energy (KE) and potential energy (PE) (elastic and gravitational)

Question 5

What is meant by natural frequency?

Answer 5

The frequency of free oscillations

Question 6

What is meant by damping?

Answer 6

The dying away of the amplitude of free oscillations, due to resistive forces

Question 7

What is meant by critical damping? And what is an example of this?

Answer 7

› When resistive forces are so large it prevents oscillations after being released
› Vehicle suspension is critically damped otherwise after travelling over a bump, the vehicle would keep oscillating

Question 8

What is meant by resonance? And what is an example of this?

Answer 8

› When a system (the responder), is driven (forced to oscillate) at its natural frequency, resulting in a large amplitude

› An example of this is in microwave ovens where water molecules (the responder) resonate when driven by the microwaves