Waves and Sound

Question 1

What is periodic motion? What is the motion called?

Answer 1

The pattern of motion repeating itself at regular intervals. Cycle or Vibration.

Question 2

What are the 2 types of vibrations?

Answer 2

Transverse which travels perpendicular (up and down) along the medium. Longitudinal which travels parallel along the medium

Question 3

What is the Rest Position/ Equilibrium Position?

Answer 3

The place where the object will naturally not move.

Question 4

What is Amplitude?

Answer 4

The maximum distance of the vibrating object from it’s rest position.

Question 5

Crest vs Trough

Answer 5

The amplitude above (crest) and below (trough) the rest position.

Question 6

What is frequency? What is it measured in?

Answer 6

Frequency is the number of cycles that occur in a unit of time. Measured in Hertz (Hz).
1Hz = 1s^-1

Question 7

Where have you seen vibrations in the real world?

Answer 7

swings, walking, tides, yo-yo, humming bird’s wings, pendulum

Question 8

What is a wave?

Answer 8

The transfer of energy (by a series of vibrations) in the form of a disturbance, usually through a material medium.

Question 9

What are the 2 types of waves?

Answer 9

Transverse waves - the motion of the medium is at right angles to the direction of the wave travel
Longitudinal waves - the motion of the medium is in the same direction as the wave travel

Question 10

What is another name for a transverse wave? A longitudinal wave?

Answer 10

Transverse - s or shear wave

Longitudinal - p or pressure wave

Question 11

What is a wavelength? What is it’s symbol?

Answer 11

The distance between 2 adjacent points. Lambda (upside down y shape)

Question 12

What is a natural frequency?

Answer 12

The frequency an object will vibrate at if no external force is applied.

Question 13

What equations work for both waves and vibrations?

Answer 13

T(period) = Δt/N            Period and frequency are transverse of each other
f = N/Δt
f = 1/T

Question 14

In phase

Answer 14

2 or more waves are at the same point and moving in the same direction

Question 15

Opposite wave

Answer 15

2 or more waves are always moving in the opposite direction

Question 16

Out of phase

Answer 16

2 or more waves are not at the same point and/or moving in the same direction

Question 17

Define resonance

Answer 17

The transfer of energy from one vibrating object to another object having the same natural frequency.

Question 18

The Doppler Effect

Answer 18

The change in frequency of the wave emitted by a fast moving object as it passes by you. Principal used for radar trap.

Question 19

What is Diffraction?

Answer 19

The bending of a wave as it nears an object. Waves pass through and opening larger than the wave length with little diffraction.

Question 20

Why can we hear but not see around corners?

Answer 20

Sound is able to diffract around corners and not sound because it has a bigger wave length than light.

Question 21

What happens when a wave (such as a

in a spring), hits a more dense medium? A less dense medium?

Answer 21

The reflected wave comes back inverted. The reflected wave comes back in phase.

Question 22

Define: Normal. angle of incidence, angle of reflection, propagation rays.

Answer 22

Normal: right angle to the barrier
Angle of Incidence: Angle between incident ray and normal
Angle of Reflection: Angle between reflective ray and normal
Propagation Ray: Ray that is right angle to the wave

Question 23

When does Constructive Interference occur?

Answer 23

When 2 waves push the medium in the same direction - the wave becomes bigger than either of the individuals. This can result in a super crest or super trough.

Question 24

When does Destructive Interference occur?

Answer 24

When 2 waves push the medium in opposite directions - the wave becomes smaller then either of the individual waves.

Question 25

What is a Node?

Answer 25

Point of destructive interference, no motion, wave energy is zero

Question 26

What is an Anitnode

Answer 26

Point of constructive interference, max wave motion and energy

Question 27

Speed of sound?

Answer 27

331 m/s