Chapter 4/5 Flashcards

1
Q

objects in mechanical equilibrium are

A

at rest/ not moving

- have 0 acceleration

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2
Q

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

A

changes in motion (direction or magnitude)

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3
Q

force

A

causes acceleration

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4
Q

acceleration

A

is directly proportional or the net force

ex. 3 X force = 3 X acceleration

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5
Q

Gravity/Weight

A

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)

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6
Q

Friction

A

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

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7
Q

Air Resistance

A

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

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8
Q

Normal/Support

A

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

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9
Q

Applied

A

Fa
Exerted by a person or object
Direction: Direction applied

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10
Q

Tension

A

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

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11
Q

Spring

A

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

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12
Q

Friction is a force that

A

holds back the movement of a sliding object

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13
Q

Friction acts in what direction?

A

opposite Direction to the way an object wants to slide

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14
Q

Friction is either

A

static or kinetic/dynamic/sliding

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15
Q

static friction

A

the frictional force opposing placing a body at rest into motion

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16
Q

dynamic/kinetic/sliding friction

A

the frictional force tending to slow a body in motion

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17
Q

friction can occour in what states?

A

solid, liquid and gas

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18
Q

fluid friction

A

called Drag

  • Drag is greater in water than in air
  • Dependent on SA and speed
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19
Q

Mass

A
  • 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
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20
Q

weight

A

force upon an object due to gravity

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21
Q

mass and weight are

A

directly proportional

ex mass X 2 = weight X 2

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22
Q

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

A

same

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

23
Q

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

A

the same

24
Q

mass resists

A

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

25
Q

acceleration of an object is

A
  • 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
Q

formula that represents Newton’s 2nd law of motion

A

F = (M)(A)

M = mass in kg
A = acceleration in m/s^2

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

27
Q

Galileo founded what 2 concepts?

What couldnt he explain?

A

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

28
Q

Newtons 2nd Law

A

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
Q

Mathamatically Non- free fall

A

a= Fnet = mg-R
—— ——-
m m

mg = weight
R = Air resistance
30
Q

Air drag

A
  • depends on two factors, speed and frontal area of the falling object
31
Q

when the upward drag cancels out the downward acting weight,

A

net force is 0

acceleration ends

32
Q

when the acceleration terminates

A

we say the object has reached its terminal speed/velocity

33
Q

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?

A
Who will get to 0 acceleration first?
Light woman (less air drag)

Who will have a faster terminal speed?
Heavy man

34
Q

2 factors that affect friction between solids

A

weight and surface texture

35
Q

a interaction is comprised of a pair of forces that are

A

equal in magnitude

opposite in direction

36
Q

Newton’s 3rd law of motion

A

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

37
Q

gravity is the force between

A

earth and mass on its surface

38
Q

when do we sense gravity (in general)

A

when huge masses like the earth are involved

39
Q

d2

A

1/4 F

40
Q

d2

A

1/9 F

41
Q

d2

A

1/16 F

42
Q

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

A

2F

43
Q

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

A

4F

44
Q

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

A

4 F

45
Q

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

d2

A

F

46
Q

Hooke’s law

A

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
Q

Universal gravitation

A

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
Q

Non Free fall
? acceleration
? R

A

acceleration is less than g

R = m*g

49
Q

Non Free Fall

-what is air resistance dependent on

A

surface area
speed
increases as an object picks up speed

50
Q

Non free fall

- what happens when air resistance = weight

A

acceleration stops = 0

speed = terminal speed

51
Q

Coefficient of friction

Static vs Kinetic

A
  • between 2 solids
    u(s) = static IS GREATER
    u(k) = kinetic
52
Q

Coefficient of friction

unit? shows?

A

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

53
Q

Newtons first law

A

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