Physics Unit 6 & 7 Flashcards
Law of Orbits
all planets move in an elliptical orbit, with the Sun at one focus
Law of Areas
a line that connects a planet to the sun sweeps out in equal areas in the plane of the planet’s orbit in equal times
Law of Periods
the square of the period of any planet is proportional to the cube of the semi-major axis of its orbit
Circular Orbit
potential, kinetic, and mechanical energies remain constant with time
Elliptical Orbit
potential and kinetic energies change with time (since r varies) but mechanical energy remains constant
frequency
number of cycles/oscillations per second
period
amount of time it takes to complete 1 oscillation/cycle
amplitude
max displacement from equilibrium position
phase
ωt + θ
position
x(t) = Acos(ωt + θ)
velocity
v(t) = x’(t) = -ωAsin(ωt + θ)
acceleration
a(t) = v’(t) = x’‘(t) = -ω²Acos(ωt + θ)
max velocity
A
max acceleration
ωA
max displacement
ω²A
U (SHM)
½kx² = ½kA²cos²(ωt + θ)
K (SHM)
½mv² = ½kA²sin²(ωt + θ)
Emech
½kA²
- stays constant
- same as the elastic potential energy that it started out with
At equilibrium…
maximum velocity (zero force and acceleration)
At endpoints…
maximum force and acceleration (zero velocity)
Springs in parallel
k = k1 + k2
Spring on each side of mass
k = k1 + k2
Springs in series
1/k =1/k1 + 1/k2
Simple Pendulum
a bob suspended from an unstretchable string
- restoring force is the weight of the bob directed
tangent to the swing path
Physical Pendulum
rigid body that oscillates around the point of suspension
- restoring force is the weight of the body acting through its center of mass directed tangent to the swing path
* I = Icom + Mh² and h is the distance between the center of mass and the pivot point
Torsion Pendulum
mass attached to an elastic material that oscillates in angular simple harmonic motion about the suspending material
- restoring torque is given by the twisting force in the wire which opposes the angular displacement
