Chapter 19: Oscillations

Question 1

Oscillations

Answer 1

repeated back and forth movement on either side of some equilibrium position

Question 2

Free oscillation

Answer 2

Continues to vibrate after energy input with a natural frequency

Question 3

Forced oscillation

Answer 3

Vibrates with continuous energy input with an unnatural frequency

Question 4

Observing oscillations

Answer 4

More than 5Hz, is a blur

Question 5

Describing oscillation

Answer 5

Accelerated towards centre. 
Fastest there. 
Decelerates towards the end. 
Stops at extreme position.
Reverses direction
Accelerates towards centre.

Question 6

What does displacement time graph show

Answer 6

Period
Frequency
Amplitude

Question 7

Phase

Answer 7

Point that an oscillating mass has reached within the complete cycle of an oscillation.

Question 8

Phase difference

Answer 8

Phase difference between 2 oscillations in degrees/radians

Question 9

Requirements for simple harmonic motion

Answer 9

Oscillating mass
Equilibrium position
Restoring force

Question 10

Changes in velocity in shm

Answer 10

Velocity is changing
Swing right to left: -v 
Accelerates towards equilibrium
Decelerates end of oscillation
Swing left to right: +v 
Maximum speed through equilibrium
Decelerates swinging up from equilibrium

Question 11

X-t graph shm

Answer 11

Sinusoidal sine curve

Motion to start is when mass is at midpoint of its oscillation moving to the right.

Question 12

V-t shm

Answer 12

Gradient of x-t
Mass is at equilibrium, moving fastest
Velocity has maximum value, positive value
t=0 is moving to the right

Question 13

a-t shm

Answer 13

Equilibrium position no resultant force, no a,
moves to the right, restoring force to the left: -a
Acceleration greatest value at greatest displacement.
a proportional to -x

Question 14

Angular frequency

Answer 14

f = 1/T 
w = 2 pi f 
w = 2 pi/ T 
T = 2 pi/ w

Question 15

Equations of shm

Answer 15

Sine: x = Amplitude sin wt
Cosine: x = Amplitude cos wt

Question 16

Acceleration and displacement

Proportionality and equation

Answer 16

A depends on displacement and magnitude of restoring force.
Greater the x, the greater the a
a = -w^squared x
Minus sign: displaced to the right, acceleration is to the left
towards equilibrium position, opposite displacement

Question 17

Simple harmonic motion definition

Answer 17

A body executes shm
if it’s acceleration is directly proportional
to its displacement from its equilibrium position,
and in the opposite direction to its displacement