Forces and motion Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

State the unit for speed/velocity

A

m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

State the difference between speed and velocity

A

direction is specified when talking about velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

speed =

A

distance/time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

acceleration =

A

change in velocity/time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an orbit ?

A

balance between the forward motion of the object and the force of gravity pulling it inwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is mass ?

A

amount of matter in an object

stays the same where ever you are

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is weight ?

A

the force of gravity on the object

changes on different planets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the unit for mass?

what is it measured by?

A

kg

measured using scales

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the unit for weight ?

what is it measured by?

A

n

measured using a spring balance or newton meter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

weight =

A

mass x gravitational field strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

state the gravitational field strength on earth/moon

A
earth = 10 n/kg
moon = 1.6 n/kg
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

state the straight downwards forces

A

gravity / weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

state the forwards forces

A

thrust / push / pull

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

state the slowing forces

A

drag / air resistance / friction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

State the 3 ways of friction occurring

A
  1. between solid surfaces gripping
  2. between solid surfaces sliding
  3. air resistance / drag from a fluid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is a fluid ?

A

liquid or gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define terminal velocity

A

the velocity when resistance force becomes equal to accelerating force in free fall (maximum velocity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

In free fall, what does the resistance equal?

A

resistance = weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are the factors of terminal velocity?

A

shape and surface area

more surface area = more air resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

State the First Law of Motion

A

Balanced forces means no change in velocity
no deceleration or acceleration
to keep steady speed there must be 0 resultant force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

State the Second Law of Motion

A

Unbalanced force means object will accelerate that direction

resultant forces means acceleration / decceleration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is an unbalanced force called ?

A

Resultant force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Resultant force =

N

A

mass x acceleration

F = ma

24
Q

State the Third Law of Motion

A

exerting a force onto and object, exerts the exact force onto you from the object
smaller mass will be affected more by force

25
Q

What are the vector quantities and examples ?

A

Size and direction

force, velocity, displacement, acceleration, momentum..

26
Q

What are the scalar quantities and examples?

A

Only size

mass, temp, time, length…

27
Q

What is Stopping distance ?

A

distance covered from driver spotting hazard to car coming to a complete stop

28
Q

Stopping distance =

A

Thinking distance + Braking distance

29
Q

What is Thinking distance ?

A

distance car travels from driver noticing hazard to applying brakes

30
Q

State the factors of thinking diatance

A
speed of car
reaction time (drugs/alcohol, tiredness, old age)
31
Q

What is Braking distance ?

A

distance car travels during deceleration until complete stop with brakes being applied

32
Q

State the factors of braking distance

A

speed of car
mass of vehicle
condition of brakes
grip (road, tyres, weather conditions)

33
Q

momentum =

A

mass x velocity

34
Q

what is the unit for momentum ?

A

kg m/s

35
Q

momentum before =

A

momentum after

36
Q

what causes change in momentum ?

A

force(s)

37
Q

Force (acting) =

A

change in momentum / time

38
Q

Describe how crumple zones help

A

crumple on impact

increase time taken for car to stop

39
Q

Describe how seat belts help

A

stretch slightly, increasing time taken for wearer to stop

reduces force acting on chest

40
Q

Describe how air bags help

A

slow you down more gradually

increase time taken for force to reach you

41
Q

why increase time taken for force to reach you (like in a crash)?

A

faster the momentum changes, larger the forces act on you and more likely to injure you
longer it takes for change in momentum, smaller the forces are

42
Q

what is a moment ?

A

the turning effect of a force

43
Q

State the unit for a moment

A

Nm

44
Q

Moment =

A

force x perpendicular distance between line of action and pivot

45
Q

state the principal of moments

A

Total anticlockwise moments = Total clockwise moments

46
Q

Your younger brother weighs 300 N and sits 2m from pivot. You weigh 700 N, where should you sit?

A

anticlockwise moment = clockwise moment
300 x 2 = 700 x y
y = 0.86m

47
Q

What happens if the anticlockwise moments don’t equal clockwise moments ?

A

there will be a resultant moment

object will turn

48
Q

what is the natural length (l) ?

A

length of an unstreched metal wire

49
Q

What is a galaxy ?

A

large collection of stars

50
Q

What are comets ?

A

small lumps of icy rock which orbit the Sun

51
Q

What happens to an orbit as gravity increases ?

A

The speed of the orbit increases

52
Q

What is the orbit shape of moons and planets ?

A

slightly elliptical

53
Q

Describe the orbit of comets

A

very elliptical and with the Sun at one end

travel much faster near the Sun as increased gravity speeds it up

54
Q

What artificial satellites have an orbital period of 1 day?

A

geostationary satellites

useful for communications

55
Q

Orbital speed =

A

(2 x π x orbital radius) / time

56
Q

what is Hooke’s law ?

A

extension of a stretched wire (or spring) is proportional to the load/force

57
Q

what is the elastic limit ?

A

point where if you increase the force more the material will be permanently stretched and longer than its natural length