Trimester 1 - Speed of Sound, Sound, Wave Interaction, Wave Speed, Waves and Vibrations, Newton's Laws of Motion, Velocity and Acceleration
What is Newton's first law?
(Inertia) An object in motion stays in motion, UNLESS acted upon by a net force.
What are the three ways to accelerate?
- Speed up - Slow down/decelerate - Changing direction
Matt drives Nascar on the weekends. If he complete 500 laps in 3 hours, each lap is 1600 m, what is his average velocity for the entire race?
-> v = 0 m/s
Harry the turtle walks with a distance of 5 meters in 10 minutes. What is his average speed in meters per second?
0.0083 m/s
Find the wavelength of the ultrasonic wave emitted by a bat if it has a frequency of 4.0 x 104 Hz.
0.0085 m
Dogs are able to hear much higher frequencies than humans are capable of detecting. For this reason, dog whistles that are inaudible to the human ear can be heard easily by a dog. If a dog whistle has a frequency of 3.0 x 104 Hz, what is the wavelength of the sound emitted?
0.011m
A wave has a wavelength of 0.044 m and a frequency (f) 13.5 hz. Calculate its speed.
0.59m/s
What is the equation to find the period of a wave?
1/frequency
What is the equation to find the frequency of a wave?
1/period
A wave with a known wavelength of 1.35 m is found to have a velocity of 175 m/s. What is the frequency of this wave?
130 Hz.
A wave traveling at 100 m/s is found to have a frequency of 5 vibrations per second. What is the wavelength of this wave?
20m
About how fast does sound travel?
340 m/s
A popular pastime at sporting events is "the wave", a phenomenon where individuals in the crowd stand up and sit down in sequence, causing a giant ripple of people. If a continuous "wave" passes through a stadium of people with a speed of 20 m/s and a frequency of 0.5 Hz, what is the distance from "crest" to "crest" (in other words, the wavelength of the wave?)
40 m
Kate's pet iguana, Ivan the destroyer, can run across water at 15 m/s. How long does it take him to slow down from 15 m/s to rest if he can accelerate at -2.5 m/s2?
6 seconds
How does a radio loud speaker work?
A cone that vibrates in sync with electric signal, causing neighboring air molecules to vibrate, and eventually sound fills the room
What is a wave?
A disturbance that travels through a medium from one location to another
Friction
A force that opposes motion between two surfaces that are in contact
What kind of wave is sound?
A longitudinal wave
Weight
A measure of the force of gravity on an object
What produces a wave?
A motion of disturbance
Where does a wave come from?
A particle which is moves away from its resting position
What is compression?
A push in the air in
What is rarefaction?
A push of the air out
What is a force?
A push or pull
Vector Quantity
A quantity that has both a magnitude and direction.
What kind of quantity is velocity?
A vector quantity
Gravity
Around 10m/s^2
When two waves overlap it can be one of what two reactions?
Constructive interference, or destructive interference
How do you find the frequency of original vibration?
Frequency of sound waves = pitch
What does the frequency tell us about pitch?
Higher frequencies have higher pitches, lower frequencies have lower pitches
Time and frequency are what?
Inverses of one another
What is a longitudinal wave?
It displaces from its rest position then returns to it
How does the noise of the sound affect speed?
It does not loud and soft sounds travel at the same speed, noise only affects amplitude
What happens anytime something is moving through the air?
It is accelerating
How do you find the frequency of a sound wave?
It is the distance between the waves
What are the two kinds of waves?
Longitudinal waves, and traverse waves
What is the trough of a wave?
Lowest point of a wave
What are the two equations to calculate net force?
Mass x Acceleration; applied force - friction force
Weight
Mass x Gravity
Force
Mass x acceleration
What is amplitude?
Maximum distance a wave varies from its rest position
How does a tuning fork produce pitch?
Prong vibration is similar to a door opening and closing created some pockets of air molecules bundled very closely together
Equilibrium
Resting position
What is the symbol for period?
T
What can change the speed of sound?
Temperature, altitude, and the medium
If the acceleration equals 0 what does that tell us about the Fnet?
That it equals 0
What is refraction?
The bending of light
What is displacement?
The change in position of an object.
What is the Doppler Effect?
The change of pitch of a wav because the An observed change in the frequency of a wave when the source or observer is moving
Net force
The combination of all forces acting on an object
When the source of the sound is moving what changes?
The frequency and pitch
Does the Doppler effect change the speed of the wave? The frequency and the wavelength of the perceived wave as the source moves towards the observer?
The frequency and wavelength of the sound wave are affected but the speed of the way stays the same
What is distance?
The length of a path between two points
What happens to an object with unbalanced forces?
The motion of the object changes
What is wave frequency?
The number of waves passing a fixed point per second.
What happens to an object with balanced forces?
The object will experience no changes in motion
What is a transverse wave?
The pulse travels perpendicularly to the disturbance
What direction does compression and rarefaction travel in?
The same direction
What is a forced vibration?
The setting up of vibrations in an object by a vibrating force
When the source of the sound is moving what does not change?
The speed of the sound of any pitch
What is physics?
The study of motion
Inertia
The tendency of an object to resist a change in motion
What is constructive interference?
The waves will add together to construct a greater amplitude when overlapping, but original waves return afterwards
What is destructive interference?
The waves will cancel each other when the positive overlaps the negative points and visa versa
What is the origin of sound?
Vibrations of objects
What is reflection?
When light bounces off an object
What is indifference?
When waves meet while traveling the same medium
Amy loves racing go karts in her free time. If she slows down from 25 m/s to 20 m/s in 1.3 s in order to make a turn, what is her acceleration while slowing down?
a = - 3.88 m/s^2 <---------------
Applied Force
a force which is applied to an object by a person or another object
What is the period in seconds for each of the following frequencies? a. 10Hz b. 0.2Hz c. 60Hz
a) T = 0.1s b) T = 5s c) T = 0.017s
A piano with a mass of 1000 kg is being pulled lowered out of a window by a rope at a constant velocity. A) Draw a free-body diagram and label all of the forces. B) What is the weight of the piano? C) What is the net force on the piano? D) What is the tension in the rope?
a) ^ I [] Fnet = 0 I v fg = 10,000 N b) 10,000 N I v c) fnet = 0 d) Fnet = 60N ---> ^ e) Ftension - 10,000 N I
A box with a weight of -200 N is being pulled across the floor horizontally. The tension in the rope pulling the box is 100 N, and the box is accelerating at 3 m/s2. A) Draw a free-body diagram and label all of the forces (including friction). B) What is the mass of the box? C) What is the normal force? D) What is the net force on the box? E) What is the friction force on the box?
a) fn = 200n I ffr = -40n- [] - fa = 100n I fg = 200n b) 200kg ^ c) fn = 200N I d) Fnet = 60N ---> e) FA = 40n <---
A rightward force is applied to a 5-kg object to give the object an acceleration of 2 m/s2. There is a frictional force of -5 N. A) Create a free body diagram B) What is the weight of the object? C) What is the normal force on the object D) What is the net force on the object? E) What is the applied force on the object?
a) fn = 50n I ffr = -5n- [] - fa = 15n I fg = 50n b) 50 N I v ^ c) fn = 50N I d) Fnet = 10N ---> e) FA = 15n --->
Rex the dog, can accelerate at 3 m/s2. If Rex accelerates for 7 seconds... a) How fast is he going if he started accelerating from rest? b) How fast is he going if he started accelerating while traveling at 4 m/s?
a) vf = 21 m/s b) vf = 25 m/s
If the frequency of a wave is doubled and if the speed remains constant, its wavelength is a. quartered. b. halved. c. unchanged. d. doubled.
b
What is the frequency of a water wave that has a speed of 0.4 meter per second and a wavelength of 0.02 meter? a. 10 hertz. b. 20 hertz. c. 0.008 hertz. d. 0.5 hertz.
b
A period of 0.005 s yields a frequency of a. 20 HZ b. 50 Hz c. 200 Hz d. 500 Hz e. 2000 Hz
c
Which phenomenon is produced by two or more waves passing simultaneously through the same region? a. refraction. b. diffraction. c. interference. d. reflection.
c
acceleration =
change in velocity / time taken
A source S generates circular waves on a lake. If the frequency of the source is 2.0 Hz and the wave speed is 5.0 m/s then the distance between adjacent wave crests is a. 0.20 m. b. 0.40 m. c. 1.25 m. d. 2.5 m. e. 10 m.
d
The number of cycles of a wave occurring per unit time is called the wave's a. wavelength. b. period. c. amplitude. d. frequency.
d
How do you calculate wave speed?
d/t
velocity =
displacement/time
speed =
distance/time
What is transferred through a wave?
energy
If the period is small the frequency is _____
high
What is the velocity of a wave?
length of pulse/time for pulse to move past a fixed point
What unit is used for acceleration?
m/s^2 (metres per second squared)
What is a scalar quantity?
only magnitude (like speed)
velocity
speed in a given direction
What is reverberation?
the bouncing back & forth of echoes between two strong reflectors
Normal Force
the force perpendicular to a surface that prevents an object from falling through the surface a force that acts on a surface in a direction perpendicular to the surface
What is the crest of a wave?
the highest point of a wave
acceleration
the rate at which velocity changes
What is wave period?
the time interval between the passage of successive crests at a stationary point
What does hertz mean?
the unit of frequency, equal to one cycle per second
What are two equations to find velocity?
v = λ/t v = fλ
What is the symbol for wavelength?
λ
