Physics Unit 6 & 7

Question 1

Law of Orbits

Answer 1

all planets move in an elliptical orbit, with the Sun at one focus

Question 2

Law of Areas

Answer 2

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

Question 3

Law of Periods

Answer 3

the square of the period of any planet is proportional to the cube of the semi-major axis of its orbit

Question 4

Circular Orbit

Answer 4

potential, kinetic, and mechanical energies remain constant with time

Question 5

Elliptical Orbit

Answer 5

potential and kinetic energies change with time (since r varies) but mechanical energy remains constant

Question 6

frequency

Answer 6

number of cycles/oscillations per second

Question 7

period

Answer 7

amount of time it takes to complete 1 oscillation/cycle

Question 8

amplitude

Answer 8

max displacement from equilibrium position

Question 9

phase

Answer 9

ωt + θ

Question 10

position

Answer 10

x(t) = Acos(ωt + θ)

Question 11

velocity

Answer 11

v(t) = x’(t) = -ωAsin(ωt + θ)

Question 12

acceleration

Answer 12

a(t) = v’(t) = x’‘(t) = -ω²Acos(ωt + θ)

Question 13

max velocity

Answer 13

A

Question 14

max acceleration

Answer 14

ωA

Question 15

max displacement

Answer 15

ω²A

Question 16

U (SHM)

Answer 16

½kx² = ½kA²cos²(ωt + θ)

Question 17

K (SHM)

Answer 17

½mv² = ½kA²sin²(ωt + θ)

Question 18

Emech

Answer 18

½kA²
- stays constant
- same as the elastic potential energy that it started out with

Question 19

At equilibrium…

Answer 19

maximum velocity (zero force and acceleration)

Question 20

At endpoints…

Answer 20

maximum force and acceleration (zero velocity)

Question 21

Springs in parallel

Answer 21

k = k1 + k2

Question 22

Spring on each side of mass

Answer 22

k = k1 + k2

Question 23

Springs in series

Answer 23

1/k =1/k1 + 1/k2

Question 24

Simple Pendulum

Answer 24

a bob suspended from an unstretchable string
- restoring force is the weight of the bob directed
tangent to the swing path

Question 25

Physical Pendulum

Answer 25

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

Question 26

Torsion Pendulum

Answer 26

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