Intro to Waves

Question 1

When an object repeats a pattern of
motion, we say that it exhibits _______ ______.

Answer 1

periodic motion

Question 2

periodic motion

Answer 2

occurs when a movement repeats itself in regular time intervals.

Question 3

The repeated pattern is called a _____

Answer 3

cycle

Question 4

Objects that exhibit periodic motion
usually are ________ or ________.

Answer 4

vibrating; oscillating

Question 5

A vibration is a cyclical motion around
some ___________ _______.

Answer 5

equilibrium point

Question 6

transverse vibrations

Answer 6

Motion is at a 90° to its length

Question 7

longitudinal vibrations

Answer 7

Motion is parallel to its length

Question 8

torsional vibrations

Answer 8

Object twists around its axis at the rest position

Question 9

The ________ is the maximum distance
from the rest or equilibrium position

Answer 9

Amplitude

Question 10

The _________ is the time needed to
complete 1 cycle.

Answer 10

Period (T)

Question 11

Frequency (f)

Answer 11

the number of cycles that occur in a unit of time

Question 12

Two identical pendulums are said to be
vibrating __ _____ if they have the same
period and pass through the rest position
at the same time.

Answer 12

in phase

Question 13

They are vibrating ___ __ ______ if they do not have the same period or if they have the same period but they do not pass through the rest position at the same time.

Answer 13

out of phase

Question 14

A _________ _____ is a disturbance
that transfers energy through a ________
(solid, liquid, or gas) by means of a
series of vibrations.

Answer 14

mechanical wave; medium

Question 15

All vibrations require a _______ in order
to transfer a ______.

Answer 15

medium; wave

Question 16

When vibrating, the medium itself does not ____ __ ____ energy.

Answer 16

gain or lose

Question 17

_______ is transmitted by the wave, but
the whole medium does not move.

Answer 17

Energy

Question 18

______ waves are waves where the
motions are repeated at regular time intervals.

Answer 18

Periodic

Question 19

However, a periodic wave can also
consist of a single disturbance called a
______-, or shock wave.

Answer 19

pulse

Question 20

A ___________ is the distance between
two points on a wave that are vibrating in
phase with each other.

Answer 20

wavelength

Question 21

how do you find the wavelength

Answer 21

It is easiest to
calculate by finding the distance from the
midpoint of one crest to the midpoint of
the next crest (or from the midpoint of
one trough to the midpoint of the next).

Question 22

A wavelength is represented by the …

Answer 22

Greek letter λ (lambda).

Question 23

A ________ wave is one in which the
medium (like air or water) vibrates at a
right angle (90º) to the direction of the
flow of energy.

Answer 23

transverse

Question 24

Each of the points along the wave is
vibrating __ ____ _____, but not moving
along the x-axis at all.

Answer 24

up and down

Question 25

The wave has some parts above the equilibrium position called _____ and some parts below the equilibrium position called _______.

Answer 25

crests; troughs

Question 26

In _________ waves, the lengths of successive crests and troughs are ______-.

Answer 26

periodic; equal

Question 27

In a _________ wave, the particles of the medium vibrate back and forth parallel to the direction of the flow of energy.

Answer 27

longitudinal

Question 28

Points at which the particles are closer together than normal are called __________.

Answer 28

compressions

Question 29

Parts where particles are farther apart than normal are called ___________.

Answer 29

rarefactions

Question 30

A ________ in a longitudinal wave is the distance between two rarefactions or two compressions.

Answer 30

wavelength

Question 31

Sound Waves – _________

Answer 31

longitudinal

Question 32

Sound Waves – longitudinal. The molecules (usually air) are displaced back and forth in the direction of the _____ __________.

Answer 32

wave motion

Question 33

Water waves – _____ ___________ .

Answer 33

mostly transverse

Question 34

Water waves – mostly transverse. But some longitudinal also. Your textbook calls these “complex waves” because they have both _________.

Answer 34

properties

Question 35

explain the difference between a wave and a vibration

Answer 35

A vibration is the cyclical motion of an object about an equilibrium point. A wave is the transfer of energy through a material due to vibration. Vibration is the cause and the wave is the effect

Question 36

What properties of a medium allow a wave to pass through most effectively? Provide an example

Answer 36

The density of the medium allows a wave to pass through most effectively. For example, a tuning fork is a solid with high density, so it sustains vibrations for longer time as waves pass through it more effectively

Question 37

Figure 6 is an image of an electric ringer inside a bell jar. A vacuum pump can be connected to the jar. You turn the ringer on, and slowly start removing the air from the bell jar. Then you slowly allow the air back in. (a) Predict how the sound from the ringer will change as you remove the air and then as you allow the air back in.

Answer 37

Sound reduces as the air is removed from the jar and increases as the air is pumped back into the jar.

Question 38

Figure 6 is an image of an electric ringer inside a bell jar. A vacuum pump can be connected to the jar. You turn the ringer on, and slowly start removing the air from the bell jar. Then you slowly allow the air back in. (b) Explain why the sound will change.

Answer 38

Sound waves require a medium to move through. As the air is removed from the jar, the density of the medium decreases so the sound decreases.

Question 39

Contrast wavelength and amplitude for longitudinal waves

Answer 39

In longitudinal waves, amplitude is the maximum pressure created and the same definition of wavelength applies.

Question 40

Contrast wavelength and amplitude for transverse waves

Answer 40

In transverse waves, wavelength is the distance between two similar points in successive identical cycles in a wave. In transverse waves, amplitude is the maximum displacement of a vibrating particle in a wave.