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Flashcards in Exam 1 Deck (50):
1

Is mass/energy conserved?

no; energy cannot be created or destroyed, it can only be changed from one form to another

2

energy

the capacity to do work

3

kinetic

energy of moving objects

4

potential

potential of an object to move

5

Why did the ancient greeks put the Earth at the center of the Universe

1. from the view of earth, sun appears to revolve around th earth once per day
2. earth does not seem to move from perspective of earth bound observer

6

What is retrograde motion

The apparent motion of a planet opposite the direction of other bodies within a system

7

What are Galilean moons

Io, Europa, Gangmede, Callisto
were not getting left behind as earth moved

8

How do the phases of mercury support a heliocentric universe

phases could only occur as Galileo saw them if Venus is circling the sun and not earth

9

What is conservation law

energy cannot be created or destroyed, it can only be changed from one form to another

10

What is a reference frame?

coordinate systems with axes emanating from a point known as origin?

11

Of location, velocity, and time, which will two observers with different reference frames agree on

velocity

12

1. coriolis force ( centrifugal force)
2. why does running water start to rotate

1. apparent force that acts outward on a body moving around a center, arising from the body's inertia.
2. rotation of the earth gives rise to an effect that tends to accelerate draining water in a clockwise direction in the Northern hemisphere and counterclockwise in the Southern

13

What are the units of position, velocity and acceleration?

position: meter (m)
velocity: seconds (s)
acceleration: meters per second (m/s)

14

How to calculate average velocity?

displacement/change in time

15

How to calculate average acceleration?

change in velocity/change in time

Vf-Vi/Tf-Ti

16

What is the diff btwn avg and instantaneous quantities

avg: mean over time interval
instantaneous: the value at some instant in time

17

What is uniform motion?

if object travels equal distances in equal intervals of time

Galileo: requires no explanation; Change in motion requires explanation

18

Galilean Relativity

Any 2 observers movng at a constant speed and direction with respect to one another will obtain the same results for any motion experiment
-All motion is relative. You have to define a frame of
reference.

19

Centripetal

The force that makes a body follow a
curved path. For example, you can calculate the
centripetal force on the earth as it orbits around the
sun --- REAL

20

Centrifugal

A force that (apparently) pushes a
body away from the axis of rotation. Like an object
flying off a spinning platter -----FAKE

21

You are on a plane at cruising altitude (with no turbulence).
You toss a peanut straight up into the air. The peanut lands:

in your mouth

22

You are on a plane at cruising altitude (with no turbulence).
You toss a peanut straight up into the air. While the peanut is in
the air, the plane starts to bank to the right. The peanut lands:

to your left

23

Newton’s First Law

Law of inertial bodies:

Bodies in motion tend to stay in motion, bodies at
rest tend to stay at rest. (Which is another way to
state Galileo’s notion that uniform motion is a
natural state of an object.)

***if a body’s
instantaneous velocity is constant, then the sum of
the forces acting on the body are zero

24

Newton’s Second Law

The rate of change of
momentum of a body is
proportional to the total
force acting on the body

F=m*a

25

momentum

mass x velocity (p=v*m)

26

Hooke's Law

The force a spring exerts is proportional to the amount the spring is stretched

27

Newton’s Third Law

When one body exerts a force on a second body,
the second body simultaneously exerts a force
equal in magnitude and opposite in direction on the
first body.

28

Universal Law of Gravity

Fg = GM1M2/
R2


• Fg = force of gravity
• M1 = larger mass
• M2 = smaller mass
• R = separation
between the two
masses
• G = universal
gravitational
constant, or
Newton’s constant or
“Big G”

29

“inverse-square law”.

gravity had to decrease as objects gotfurther away

30

Wave

A disturbance that travels through a
medium, transporting energy (not mass)

31

Constructive interference

the waves add together
to make a single bigger wave

32

Destructive interference

waves cancel each other
and the wave goes away.

33

Major discoveries of
electricity and magnetism

• electric charges exert forces on one another
• magnetic poles exert forces on one another
• moving electric charges gives rise to magnetism
• changing magnetism gives rise to electricity


• A changing magnetic field creates an electric field
• A changing electric field creates a changing
magnetic field.
• The oscillations should be self-perpetuating.
• Mechanical waves eventually peter out. E&M
waves should propagate forever.

34

speed of light

186,000 miles per hour
3x10^8 meters per second

frequency times the
wavelength is the speed of light.

35

waves

(longer) radio waves, microwaves, infrared, visible, uv rays, soft, hard xrays, gamma rays (shorter)

36

“blackbody”

object that absorbs all
light that hits it, energy absorbed is re-emitted

distribution of the energy (ie, the distribution
of the wavelengths of light) is in thermal
equilibrium.

37

Thermal equilibrium

distribution of the energy (ie, the distribution
of the wavelengths of light)

some amount of light comes out at all wavelengths

where that distribution peaks depends on
the temperature of the blackbody.

38

The “peak” of thermal equilibrim moves

to the left as Temp
goes up

39

is the speed of light finite? How do we measure the speed of light

yes, measure the angle for starlight + speed of earth around the sun

40

field

physical quantity that has a value for each point in space and time

41

action at a distance

pbject can be moved, changed or otherwise affected without being physically touched by another object

42

whAT does it meant hat EM waves are self-perpetuation

EM waves can travel through empty space even in the absence of moving chrges or currents with the electric field component and the magnetic field component each continually changing + perpetuating each other

43

electromagnetic spectrum
what creates waves n each part of the spectrum

range of wavelengths, frequencies over which EM rRADIATion extends
2. radiation

44

ether

medium through which light propagates

-We needed a reference frame for the speed of
light. (“c relative to what?”)
-knew that light speed didn’t combine with the
speed of the emitter

45

Doppler Shift

If an emitter of sound (or a receiver of the sound)
is moving, the time between receiving successive
waves will change. Thus, the frequency of the wave
will change.

46

Michelson-Morley
Experiment

Experiment designed to measure our speed
through the ether.

If light is c relative to ether, then light relative to us
will be different in the direction of our velocity than
at a 90 degree angle to our velocity

Different speeds mean different times to reach the
screen in the interferometer, meaning the waves will
not be in phase: interference!

47

Michelson-Morley
Experiment: Result

Waves were in phase.

48

Einstein Relativity

Laws of all physics are the same
regardless of reference frame.

49

Photoelectric Effect

Light acts like a particle. It’s like a little ball of
energy. The energy is proportional to the
frequency: e=hxf

light only exists in discrete
“packets” of energy. Also known as “light quanta”.
Let’s call this light particle a “photon”

The electrons are bound to an
atom. If the the energy of the
photon is greater than the
“binding” energy, the photon can
strip the electron out of the atom.
• Only one photon can interact
(“hit”) with the electron at a time.
If the energy of the photon is less
than the energy required to free it
from the atom, it won’t come out
no matter how many photons are
thrown at the atom

50

Wave-Particle Duality

light could be both a particle
and a wave.
• When we need it to be a particle, it’s a particle.
• When we need it to be a wave, it’s a wave.