(L10) Mechanics 6 - SHM / Waves Flashcards
What is Hooke’s law?
For spring and many other materials, the lenth change is proportional to magnitude of the restoring force.
F= -kx
k is the spring constant
What if there’s suspension involved and we need to find k?
Use F=mg as the mass will be affected by gravity.
Rearragne F= -kx to find k=-(F/x)
then solve for k
As spring is compressed/stretched by force, F, how can we find work done on spring?
W=Fd –> W=1/2k*x^2
Remember that work = Potential Energy stored.
What is PE/W equation in SHM?
PE = 1/2kx^2
W = 1/2kx^2
or PE = 1/2kA^2
How to find PE of compressed/stretched string using W?
Find the work, as W=PE.
What is SHM/what causes oscillation?
A mass attatched to a spring will always experience a restoring force back towards its equilbrium position, if displaced.
Hence, it will oscillate.
What does sinusoidally mean?
related to or shaped like a sine curve.
Describe oscillation shape if
F = − kx
The mass on a spring will oscillate sinusoidally with simple harmonic motion.
What is the period, T?
Time taken for each full cycle of oscillation.
2s period means 0.5hz frequency
What is the frequency, f?
the number of cycles of oscillation per second
0.5s period means 2hz frequncy
What is energy and velocity like at centre of oscillation? In equilibrium position?
No PE, only KE.
Velocity is at max.
total E = 1/2mv,max^2
What is energy and velocity like at ends of oscillation? In max distance position?
No KE, only PE
velocity is at 0.
total E = 1/2kA^2
A being amplitude
What is total energy, with Amplitude displacement being anywhere?
Total Energy in the (general) position shown = PE + KE
E = 1/2kx^2 + 1/2mv^2
What is v,max equation for a spring of SHM?
What is period equation using m/k for a spring in SHM?
What is frequency equation for a spring using m/k in SHM?
What is the period for a simple pendulum?
What is the restoring force of a pendulum?
Restoring force is T,horizontal = -kx
What is λ?
Used to denote wavelength.
1/2 λ is 1/2 T
1 full λ is one full cycle of oscillation.
What is amplitude?
Half the wavelenth.
Distance from equilibrium to max.
What are transverse waves?
Oscillation is transverse (perpendicular) to propogation direction.
What are longitudinal waves?
Oscillation is in direction of propogsation.
What is constructive interference?
IWave 1 and 2 in phase
Constructive or destructive interference? Why?
Destructive. The λ intergers won’t add to a whole number. So a trough will meet a peak.
Constructive or destructive interference? Why?
Constructive. The λ interfers will add to a whole number as a peak meets a peak.
What is a node?
Places where string is not moving
What is an anti-node?
Places where the string is moving
Can waves carry energy?
yess.
energy of waves fucks your ears nerves overtime
What is potential energy of a wave equation?
