Test 3 Ch.'s 12, 14, and 20 Flashcards
What is a rigid body?
a point on a body maintains its position relative to all other points on the body
CCW angular momentum
angular momentum is in the + z direction
CW angular momentum
angular momentum is in the - z direction
Parallel axis theorem
if you know the moment of inertia and want to rotate an object about something other than the center of bass;
I=I(center of mass) + md^2
What is angular velocity(omega) in terms of linear velocity?
omega=v/r
Right hand rule for torque
thumb: r
index finger: F
middle finger: torque
What must be satisfied for an object to be in static equilibrium?
Fnet=0 in the x, y and z directions
and net torque=0
equation for net torque
rFsin(theta)
When a spring is compressed;
velocity=0 max potential energy kinetic energy=0 max force max acceleration
When spring is at equilibrium;
max kinetic energy
potential energy=0
max velocity
Force=0
When spring is extended;
velocity=0 max potential energy kinetic energy=0 max force max acceleration
Amplitude
max displacement from equilibrium
measured in meters
Frequency
cycles per second
unit of hertz
Period(T)
time for 1 cycle
angular frequency
omega
units of rad/s
Restoring force
always points back towards equilibrium
Relationship between period and frequency
T=1/f
Equation for velocity in terms of simple harmonic motion
Vmax=sqrt(k/m)A=omegaA
What is angular frequency equal to in torsional SHM?
sqrt(k/I)
What is a simple pendulum?
assumes all the mass is at the end of the pendulum
3 cases of a damped oscillator
under damped
critically damped
over damped
What is a mechanical wave?
disturbance in a material(medium)
What effect does a mechanical wave have on the medium?
it causes the medium to under go SHM
What does a wave actually move?
ENERGY
Transverse wave
amplitude is perpendicular to the velocity of the wave
Longitudinal wave
amplitude is parallel to the velocity of the wave
In the equation for a wave: kx-omega*t
What direction is the wave going?
postive x direction
In the equation for a wave: kx+omega*t
What direction is the wave going?
negative x direction
what is the weird u equal to?
m/L where L is the length of the medium
Velocity of a wave on a string
sqrt(T/wierd u) where T is tension
Constructive interference
two waves come together and double
destructive interference
two waves come together and cancel out each other’s amplitude but not each other’s energy
How many nodes and antinodes in the 2nd harmonic?
2 antinodes and 1 node
How many nodes and antinodes in the 1st overtone?
2 antinodes and 1 node
linear terms to rotational terms
x->theta v->omega a-> alpha m->I (uppercase i, moment of inertia) F-> torque P(momentum)-> L (angular momentum)
Equation for rotational kinetic energy
K=(1/2)Iomega^2
Definition of torque
a force that causes rotation
Wave # k=
(2*pi)/wavelength
