Chapter 17: Oscillations

Question 1

Simple Harmonic Motion

Answer 1

An oscillation in which the acceleration of an object is directly proportional to its displacement from the midpoint, and is directed towards the midpoint

Question 2

Restoring Force

Answer 2

pushing or pulling object back towards equilibrium position, size depends on displacement and can cause acceleration

Question 3

acceleration of SHM equation

Answer 3

a = -ω^2 x
Gradient of velocity-time graph

Question 4

Displacement

Answer 4

distance from equilibrium position
Varies as a cosine or sine graph with max value A

Question 5

Amplitude

Answer 5

maximum displacement

Question 6

period

Answer 6

time taken for one oscillation

Question 7

frequency

Answer 7

number of oscillations per second

Question 8

Conditions for SHM

Answer 8

• acceleration must be directly proportional to displacement and in the opposite direction
• must always act towards the equilibrium

Question 9

Two examples of systems that undergo SHM

Answer 9

• mass-spring system
• pendulum

Question 10

True or false: velocity is maximum when displacement is maximum

Answer 10

False.
Velocity is at minimum when displacement is maximum
Velocity is max at equilibrium position

Question 11

What is damping?

Answer 11

Process by which the amplitude of the oscillator decreases over time. This is due to energy loss to resistive forces such as drag and friction

Question 12

Light damping

Answer 12

occurs naturally
amplitude decreases exponentially
Sharp resonance peak

Question 13

Heavy damping

Answer 13

amplitude decreases dramatically

Question 14

Critical damping

Answer 14

Object stopped in s short time without overshooting the pendulum

Question 15

Difference between free and forced oscillations

Answer 15

Free - oscillations without external forces, at natural frequency
Forced - periodic driving force is applied, particular frequency

Question 16

Resonance

Answer 16

Driving frequency of the external force is applied to an object is same as the natural frequency of object
no damping
amplitude of oscillation rapidly increase

Question 17

Energy changes during SHM

Answer 17

exchanges between potential energy and kinetic energy

Question 18

mechanical energy

Answer 18

sum of kinetic and potential energy

Question 19

Phase Difference

Answer 19

how much one wave lags behind another
measured in Radians

Question 20

Is there a relationship between frequency, period and amplitude?

Answer 20

No.
Frequency and period and independent of amplitude

Question 21

How do potential and kinetic energy vary through SHM?

Answer 21

• Towards equilibrium: P transferred to K
• Away from equilibrium: K transferred to P
• Equilibrium: K max and P=0
• Max displacement: K=0 and P max

Question 22

SHM Experiment

Answer 22

1) Lift mass slightly and release it. Mass-spring system will start oscillating with SHM
2) Experiment must be repeatable, place ruler behind the spring to measure how far to raise the mass
3) As mass oscillate, position sensor will measure displacement over time
4) Let experiment run until you have good amount of data
Computer will generate displacement-time graph and from graph you can obtain A and T

Question 23

What happens when damping increases?

Answer 23

• Amplitude at any frequency decreases
• Maximum amplitude occurs at a lower frequency than f0
• The peak on the graph becomes flatter and broader

Question 24

Forced Vibration

Answer 24

periodic force, alternating force applied to a mechanical system