test 2

Question 1

which is fundamental, mass or weight

Answer 1

mass

Question 2

what does weight depend on

Answer 2

gravitational acceleration

Question 3

which one is a force, mass or weight

Answer 3

weight

Question 4

which one changes if you go from earth to moon, mass or weight

Answer 4

weight

Question 5

which one stays the same, mass or weight

Answer 5

mass

Question 6

normal force

Answer 6

perpendicular interaction between surface and object
- when surface changes, so does normal force

Question 7

how do we find normal force

Answer 7

summing forces in the actual or rotated Y direction

Question 8

what does normal force =

Answer 8

support force
- this is how you experience weight

Question 9

how can you weight change

Answer 9

because it is a result of summed forces

Question 10

how do you determine weight

Answer 10

based on normal force

Question 11

lbs

Answer 11

measure of weight

Question 12

kg

Answer 12

measure of mass (fundamental)

Question 13

what are the 4 elevator cases

Answer 13

1. stationary
2. acc. up
3. acc. down
4. cable snaps

Question 14

acc. up

Answer 14

n=w+may
velocity is down and want to slow down

Question 15

acc. down

Answer 15

n=wmay
velocity is up and want to slow down
- you feel lighter

Question 16

when the cable snaps, what is the force that is acting

Answer 16

only gravity

Question 17

as you move up and down in the elevator, why does weight change

Answer 17

because of acceleration

Question 18

when objects are connected by string under tension, how do they move

Answer 18

• must move together
• have same acceleration

Question 19

when deal with frictionless pulleys, the tension in the rope is what, causing the system to what

Answer 19

• tension is same
• system move together
• have same acceleration

Question 20

what are some example scenarios of equilibrium

Answer 20

• stationary
• static
• not moving
• at rest
• constant speed

Question 21

what does acceleration equal during equilibrium

Answer 21

0

Question 22

if in equilibrium, then forces pointing right=

Answer 22

all forces pointing left

Question 23

if in equilibrium, all forces pointing up=

Answer 23

all forces pointing down

Question 24

what does static friction have

Answer 24

max value of usn

Question 25

Fs

Answer 25

static friction

Question 26

if forces added together pointing right are larger than all forces added together pointing left, what happens to the object

Answer 26

accelerates to the right

Question 27

if left sum is larger than right sum, what happens to object

Answer 27

accelerates to left (negative direction)

Question 28

what are the three types of friction

Answer 28

static dynamic rolling

Question 29

which type of friction is for stationary objects

Answer 29

static standing

Question 30

which type of friction is for object sliding across surface

Answer 30

dynamic

Question 31

which friction force is smaller for rolling or sliding object

Answer 31

rolling

Question 32

what two quantities does friction force depend on

Answer 32

normal and coefficient of friction

Question 33

what quantity is determined by two materials in contact with each other

Answer 33

coefficient of friction

Question 34

static friction

Answer 34

- opposes net force on the object if object is not in motion fs

Question 35

kinetic friction

Answer 35

opposes velocity vector if object is in motion fk=ukn

Question 36

can you have mutliple types of friction working at a time

Answer 36

no, can only have 1

Question 37

coefficient of static or kinetic

Answer 37

- dimensionless number - property of 2 materials in contact (object and surface)

Question 38

friction

Answer 38

parallel interaction between object and surface

Question 39

when does static become friction

Answer 39

static will match number until pull is at the max value

Question 40

Fp>Fsmax

Answer 40

object is moving

Question 41

inertial drag

Answer 41

object moving through fluid had to physically move atoms out of way Re>1000

Question 42

viscous drag

Answer 42

material in liquid is sticking to object so slowing object down - viscosity of fluid - Re<1

Question 43

Cd

Answer 43

- form factor of object - related to shape of object - squares are bad because they catch more air - pointy objects have better Cd

Question 44

moving up

Answer 44

negative

Question 45

moving down

Answer 45

positive

Question 46

terminal speed

Answer 46

- when mg=0 or ay=0 - object stops accelerating because velocity is fixed

Question 47

when moving in a circle at a constant speed, what should cancel

Answer 47

mass

Question 48

what acceleration is responsible for changing direction of velocity vector

Answer 48

centripetal or radial

Question 49

when summing forces in radial direction, which direction is that

Answer 49

towards center

Question 50

what holds a car in a circular path when making a turn

Answer 50

static friction

Question 51

what happens to car if force is not large enough

Answer 51

will slide out of path

Question 52

period

Answer 52

T - time required for one complete cycle

Question 53

frequency

Answer 53

number of events that occur per second - measured in Hz

Question 54

angular speed

Answer 54

- omega - how quickly something rotates

Question 55

centripetal acceleration

Answer 55

velocity changes requires acceleration - directional change only - points toward center of curve

Question 56

what does size of acceleration depend on for centripetal acceleration

Answer 56

how fast your going and size of turn

Question 57

towards center

Answer 57

positive

Question 58

away from center

Answer 58

negative

Question 59

nickname for third law

Answer 59

law of action - reaction or law of interaction

Question 60

what are the action/reaction pairs

Answer 60

the two forces that are equal and opposite

Question 61

newtons third law

Answer 61

interaction is between one thing and another and require a pair of forces action on two objects - things happen in pairs

Question 62

what is an example of newtons third law

Answer 62

interaction of hand and wall pushing on each other

Question 63

weight

Answer 63

force of gravity acting on object - acts in negative Y

Question 64

spring

Answer 64

Fs=|kx|

Question 65

tension

Answer 65

FT - string - rope - cable - acts along rope

Question 66

inertia

Answer 66

tendency of object to resist any attempt to change its velocity

Question 67

what is newtons first law of motion

Answer 67

- law of inertia - every object continues in its state of rest/uniform speed in straight line as long as no net force acts on it

Question 68

what is a force

Answer 68

- push or pull in an object - causes velocity to change - vector - causes acceleration

Question 69

what is newtons second law

Answer 69

- law of acceleration F increases, a decreases m increases, a decreases

Question 70

what are the units for Big G

Answer 70

N m^2/kg^2

Question 71

who first measured Big G

Answer 71

Henry Cavendish

Question 72

how does gravity change inside a planet

Answer 72

decreases linearly

Question 73

the orbital velocity need to maintain orbit depends on what factors

Answer 73

mass of main body and distance from its center - does not depend on mass

Question 74

does matter repulse

Answer 74

no, all matter attracts other matter

Question 75

G

Answer 75

universal gravity constant G=6.67x10^-11

Question 76

mass increases, what happens to gravity

Answer 76

force gravity increases

Question 77

as mass of one object goes up, what happens to force between them

Answer 77

also goes up (linear)

Question 78

as distance between objects goes up, what happens to force of attraction

Answer 78

goes down (inverse square)

Question 79

orbit

Answer 79

constant state of free fall