Chapter 4/5

Question 1

objects in mechanical equilibrium are

Answer 1

at rest/ not moving

- have 0 acceleration

Question 2

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

Answer 2

changes in motion (direction or magnitude)

Question 3

force

Answer 3

causes acceleration

Question 4

acceleration

Answer 4

is directly proportional or the net force

ex. 3 X force = 3 X acceleration

Question 5

Gravity/Weight

Answer 5

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)

Question 6

Friction

Answer 6

Ff
Exerted by a surface as object moves/trys to move across it
Direction: Opposite the direction of motion

Question 7

Air Resistance

Answer 7

Fair
Acts upon objects as they move through air
Affected by speed and surface area
Direction: Opposite the direction of motion

Question 8

Normal/Support

Answer 8

Fn
Force exerted to hold another object up
Direction: Perpendicular to surface

Question 9

Applied

Answer 9

Fa
Exerted by a person or object
Direction: Direction applied

Question 10

Tension

Answer 10

Ft
Transmitted through a string, rope or wire when it is pulled at each end
Direction: Pulls along direction at length

Question 11

Spring

Answer 11

Fs
Exerted by a compressed or stretched spring
Direction: direction of restoring it back to original position

Question 12

Friction is a force that

Answer 12

holds back the movement of a sliding object

Question 13

Friction acts in what direction?

Answer 13

opposite Direction to the way an object wants to slide

Question 14

Friction is either

Answer 14

static or kinetic/dynamic/sliding

Question 15

static friction

Answer 15

the frictional force opposing placing a body at rest into motion

Question 16

dynamic/kinetic/sliding friction

Answer 16

the frictional force tending to slow a body in motion

Question 17

friction can occour in what states?

Answer 17

solid, liquid and gas

Question 18

fluid friction

Answer 18

called Drag

• Drag is greater in water than in air
• Dependent on SA and speed

Question 19

Mass

Answer 19

• 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

Question 20

weight

Answer 20

force upon an object due to gravity

Question 21

mass and weight are

Answer 21

directly proportional

ex mass X 2 = weight X 2

Question 22

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

Answer 22

same

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

Question 23

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

Answer 23

the same

Question 24

mass resists

Answer 24

acceleration
- the acceleration produced is inversely proportional
As mass increases, acceleration decreases

Question 25

acceleration of an object is

Answer 25

- 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

Question 26

formula that represents Newton's 2nd law of motion

Answer 26

F = (M)(A) ``` M = mass in kg A = acceleration in m/s^2 ``` kg*m/s^2 is known as a Newton (N)

Question 27

Galileo founded what 2 concepts? | What couldnt he explain?

Answer 27

Inertia and acceleration (and was first to measure acceleration of falling objects) Why objects with different masses fall with equal acceleration

Question 28

Newtons 2nd Law

Answer 28

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

Question 29

Mathamatically Non- free fall

Answer 29

a= Fnet = mg-R ------ ------- m m ``` mg = weight R = Air resistance ```

Question 30

Air drag

Answer 30

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

Question 31

when the upward drag cancels out the downward acting weight,

Answer 31

net force is 0 | acceleration ends

Question 32

when the acceleration terminates

Answer 32

we say the object has reached its terminal speed/velocity

Question 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?

Answer 33

``` Who will get to 0 acceleration first? Light woman (less air drag) ``` Who will have a faster terminal speed? Heavy man

Question 34

2 factors that affect friction between solids

Answer 34

weight and surface texture

Question 35

a interaction is comprised of a pair of forces that are

Answer 35

equal in magnitude | opposite in direction

Question 36

Newton's 3rd law of motion

Answer 36

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

Question 37

gravity is the force between

Answer 37

earth and mass on its surface

Question 38

when do we sense gravity (in general)

Answer 38

when huge masses like the earth are involved

Question 39

Gm*m ? F if you double the distance (m, m, 2d) ------- d2

Answer 39

1/4 F

Question 40

Gm*m ? F if you triple the distance (m, m, 3d) ------- d2

Answer 40

1/9 F

Question 41

Gm*m ? F if you quadruple the distance (m, m, 4d) ------- d2

Answer 41

1/16 F

Question 42

? F if you double one of the masses (2m, m, d) Gm*m ------- d2

Answer 42

2F

Question 43

? F if you double both masses (2m, 2m, d) Gm*m ------- d2

Answer 43

4F

Question 44

? F if you cut the distance in half (m, m, d/2) Gm*m ------- d2

Answer 44

4 F

Question 45

? F if you double both masses and dist. (2m 2m 2d) Gm*m ------- d2

Answer 45

F

Question 46

Hooke's law

Answer 46

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)

Question 47

Universal gravitation

Answer 47

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

Question 48

Non Free fall ? acceleration ? R

Answer 48

acceleration is less than g | R = m*g

Question 49

Non Free Fall | -what is air resistance dependent on

Answer 49

surface area speed increases as an object picks up speed

Question 50

Non free fall | - what happens when air resistance = weight

Answer 50

acceleration stops = 0 | speed = terminal speed

Question 51

Coefficient of friction | Static vs Kinetic

Answer 51

- between 2 solids u(s) = static IS GREATER u(k) = kinetic

Question 52

Coefficient of friction | unit? shows?

Answer 52

shows how much resistance you're going to recieve from 2 surfaces - no units Ff = u(Fn)

Question 53

Newtons first law

Answer 53

Every object continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by force impressed upon it