Unit C 1-5 Flashcards
What are the conditions for simple harmonic motion?
Acceleration is proportional to displacement
There is always a restoring force wants to get back to equilibrium
What does the x - a graph for SHM look like?
It looks like a cosine graph
How do time period and frequency relate?
Frequency is one divided by the time period.
What does the time period for the simple pendulum and the mass on a spring system depend on
It depends on the length of the string pendulum.
What are the energy changes that take place in the simple pendulum and the mass on a spring system?
When the pendulum passes through equilibrium it is at the highest kinetic energy and when it reaches the maximum amplitude it is at the highest potential energy. All of the other points have a combination of both kinetic and potential.
What are the differences between a longitudinal and transverse wave? Mechanical and Electromagnetic waves?
Longitudinal waves the energy travels parallel to the oscillation of the wave and in transverse waves the energy travels perpendicular direction as the oscillation of the waves.
Mechanical waves need to travel through a medium and electromagnetic waves can travel through a vacuum such as light (found in the electromagnetic spectrum)
What are the four things that all waves can do?
reflect, refract, diffract and superposition
What does the angle of reflection always equal?
The angle of incidence
In Snell’s law, what are the angles measured from?
From the line of origin. The line of reflection.
What is n in Snell’s law?
The refractive index of the substance.
What happens to the refracted angle when you go from slow to fast? Fast to slow?
When you go slow to fast the refracted angle decreases.
When you go fast to slow the refracted angle increases.
What is TIR and when does it occur? How do we calculate the critical angle?
From slow to fast there is a angle where the incident ray is
What is superposition?
When two waves in the same phase combine and grow 2x.
In a double-slit experiment, what is s? And what does the diffraction pattern look like?
S is the distance between one bright spot and the nearest bright spot or black spot to black spot.
How are dark and bright fringes created
Dark fringes are formed fue to deconstructive interference where the waves arrive out of phase (pi/2) and a trough and .. cancel each other out. And the bright fringes form due to constructive interference when waves arrive in phase and theu superimpose.
What does coherent mean?
Same frequency and same phase in order to see the diffraction patterns
How do we create standing waves?
Standing waves happens when an incident wave travels through a .. and when it reaches the boundary the reflected waves travel back and they superimpose.
What do the standing wave harmonics look like on a string? Open (open) pipe? Close (open) pipe? Be able to sketch these
String= waves look like sin graphs and each harmonic they grow by half of a wave.
Open (open) pipe= looks like a cos graph that each harmonic it grows by a quarter of a wave.
Close (open) pipe= looks like a cos graph that only has odd harmonics and it grows by a quarter of a wave.
How do we then relate the frequency and wavelength with the speed of sound?
The formula v (speed of sound) =frequency * wavelength
What do we mean by forced oscillations?
In resonance, forced oscillation is the force that you have to match the frequency with th enatural.
What do we mean by resonance?
Resonance: matching the frequnecy with the natural frequency in order to increase the amplitude
What do we mean by damping? What is the difference between light, heavy, and critical damping and when might we want each of these to occur?
Light damping (pendulum clock) same time period and slowly reaches 0 caused by air resistance. Reduction ion the amplitude of oscillation due to some external force
Heavy damping (shock absorbers) the time period are getting shorter and it reaches 0 faster
Critical: does not cross 0 (like the door)
What is the Doppler effect?
the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave
shot wavelength = blue
long wavelength = red
In the Doppler effect for light formula, what does the Δ sign mean?
Change
What are v and c in the formula?
c= speed of light
v= speed of observer or of the waves
When the DE is applied to things like radar, speed cameras etc why is there a factor of 2?
Because the light travels there and back
