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