Flashcards in Chapter 4/5 Deck (53):

1

## objects in mechanical equilibrium are

###
at rest/ not moving

- have 0 acceleration

2

## if there is a net force (netF = not 0) it will cause

### changes in motion (direction or magnitude)

3

## force

### causes acceleration

4

## acceleration

###
is directly proportional or the net force

ex. 3 X force = 3 X acceleration

5

## Gravity/Weight

###
Fg

Force of which an objects attracts another object to itself

Fg = (m)(g) g=acceleration of gravity 9.8m/s^s

Direction: Downward (towards earth)

6

## Friction

###
Ff

Exerted by a surface as object moves/trys to move across it

Direction: Opposite the direction of motion

7

## Air Resistance

###
Fair

Acts upon objects as they move through air

Affected by speed and surface area

Direction: Opposite the direction of motion

8

## Normal/Support

###
Fn

Force exerted to hold another object up

Direction: Perpendicular to surface

9

## Applied

###
Fa

Exerted by a person or object

Direction: Direction applied

10

## Tension

###
Ft

Transmitted through a string, rope or wire when it is pulled at each end

Direction: Pulls along direction at length

11

## Spring

###
Fs

Exerted by a compressed or stretched spring

Direction: direction of restoring it back to original position

12

## Friction is a force that

### holds back the movement of a sliding object

13

## Friction acts in what direction?

### opposite Direction to the way an object wants to slide

14

## Friction is either

### static or kinetic/dynamic/sliding

15

## static friction

### the frictional force opposing placing a body at rest into motion

16

## dynamic/kinetic/sliding friction

### the frictional force tending to slow a body in motion

17

## friction can occour in what states?

### solid, liquid and gas

18

## fluid friction

###
called Drag

- Drag is greater in water than in air

- Dependent on SA and speed

19

## Mass

###
- quantity of matter in a object

- measure of inertia or sluggishness that an object exhibits in response to any effort made to change its state of motion

ex. shaking test tests mass/ how resistant it is to change/inertia

20

## weight

### force upon an object due to gravity

21

## mass and weight are

###
directly proportional

ex mass X 2 = weight X 2

22

## Is it eaiser or harder to accelerate a car on the moon?

###
same

- the mass of the car is the same because it is independent of gravity

23

## mass of something on the moon compared to earth is..

### the same

24

## mass resists

###
acceleration

- the acceleration produced is inversely proportional

As mass increases, acceleration decreases

25

## acceleration of an object is

###
- directly proportional to the net force action on the object

- its is in the direction of the net force

- inversely proportional to the mass of the object

26

## formula that represents Newton's 2nd law of motion

###
F = (M)(A)

M = mass in kg

A = acceleration in m/s^2

kg*m/s^2 is known as a Newton (N)

27

##
Galileo founded what 2 concepts?

What couldnt he explain?

###
Inertia and acceleration (and was first to measure acceleration of falling objects)

Why objects with different masses fall with equal acceleration

28

## Newtons 2nd Law

###
The acceleration of a object is directly proportional to the net force acting on the object

It is in the direction of the net force

And inversely proportional to the mass

29

## Mathamatically Non- free fall

###
a= Fnet = mg-R

------ -------

m m

mg = weight

R = Air resistance

30

## Air drag

### - depends on two factors, speed and frontal area of the falling object

31

## when the upward drag cancels out the downward acting weight,

###
net force is 0

acceleration ends

32

## when the acceleration terminates

### we say the object has reached its terminal speed/velocity

33

##
light woman & heavy man jump out of a plane, and open same size parachutes at the same time

Who will get to 0 acceleration first?

Who will have a faster terminal speed?

###
Who will get to 0 acceleration first?

Light woman (less air drag)

Who will have a faster terminal speed?

Heavy man

34

## 2 factors that affect friction between solids

### weight and surface texture

35

## a interaction is comprised of a pair of forces that are

###
equal in magnitude

opposite in direction

36

## Newton's 3rd law of motion

### whenever one object exerts a force on a second object the second object exerts an equal and opposite force on the first object

37

## gravity is the force between

### earth and mass on its surface

38

## when do we sense gravity (in general)

### when huge masses like the earth are involved

39

##
Gm*m ? F if you double the distance (m, m, 2d)

-------

d2

### 1/4 F

40

##
Gm*m ? F if you triple the distance (m, m, 3d)

-------

d2

### 1/9 F

41

##
Gm*m ? F if you quadruple the distance (m, m, 4d)

-------

d2

### 1/16 F

42

##
? F if you double one of the masses (2m, m, d)

Gm*m

-------

d2

### 2F

43

##
? F if you double both masses (2m, 2m, d)

Gm*m

-------

d2

### 4F

44

##
? F if you cut the distance in half (m, m, d/2)

Gm*m

-------

d2

### 4 F

45

##
? F if you double both masses and dist. (2m 2m 2d)

Gm*m

-------

d2

### F

46

## Hooke's law

###
the amount of stretch in a spring is proportional to the amount of force exerted on the spring

the distance is opposite the displacement

- slope is k (spring constant)

47

## Universal gravitation

###
every object in the universe attracts every other object in the universe with a force that is directly proportional to the masses

and inversely proportional to the square of the distances betwen their centres

48

##
Non Free fall

? acceleration

? R

###
acceleration is less than g

R = m*g

49

##
Non Free Fall

-what is air resistance dependent on

###
surface area

speed

increases as an object picks up speed

50

##
Non free fall

- what happens when air resistance = weight

###
acceleration stops = 0

speed = terminal speed

51

##
Coefficient of friction

Static vs Kinetic

###
- between 2 solids

u(s) = static IS GREATER

u(k) = kinetic

52

##
Coefficient of friction

unit? shows?

###
shows how much resistance you're going to recieve from 2 surfaces

- no units

Ff = u(Fn)

53