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forces/ motion Flashcards

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1
Q

What are the units for gravitational field strength

A

N/Kg

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2
Q

How many Newton’s is 1 kg

A

10 N

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3
Q

What are the standard units for mass

A

Kg

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4
Q

What are the units for momentum

A

Kg m/s
(Kilograms metre per second)

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5
Q

What are the units for a moment

A

Nm
(Newton metre)

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6
Q

What is the formula for speed in terms of notation

A

V=S/T

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7
Q

How would you convert from m/s to km/hr

A

1) divide by 1000
2) multiply by 3600

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8
Q

Describe an experiment to find the speed of cars passing down a road

(4)

A

1) measure the distance between two points with a click wheel
2) start stop watch when car passes
2) stop stopwatch when ur passes that point
3) use you data and divide distance by time to get speed

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9
Q

Definition of displacement

A

Distance travelled in a particular direction

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10
Q

What is a vector quantity

A

Has a magnitude and direction

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11
Q

Why is average speed greater than average velocity when walking to one part of town to another

A

-You will have to cross a larger distance
- the displacement however will be less

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12
Q

How can you make human error more reliable

A

Repeat a few time
- and make an average value

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13
Q

If line of best fit is a straight line plotted through the origin, what does that suggest about about the quantities

A

They are proportional to each other

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14
Q

How do you calculate average speed with a timing gate

A

-Measure the card strip attached to the car
-measure the length of time it takes to pass the timing gate

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15
Q

What does a curve represent on a distance time graph

A

Change in speed

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16
Q

In an experiment of investigating motion, what would the independent variable be and why

A

The distance because that is what we are changing in order to see its effects on what we are measuring (the time)

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17
Q

What is the definition of acceleration

A

The rate of change of velocity

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18
Q

How is it possible to accelerate without changing your speed

A

Because you can change your direction

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19
Q

How can you find average velocity on a graph

A

Half way between the final and initial velocity

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20
Q

What is the equation for displacement

A

S = v+u/2 x t

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21
Q

What is the equation for final velocity

A

V=u +at
(Final Velocity= Initla velocity + acceleration * time

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22
Q

What are three things that a force can change

A

Speed
Shape
Direction

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23
Q

If an object accelerates does the air resistance increase or decrease

A

Increase

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24
Q

Give 5 examples of contact forces

A

Air resistance
Upthrust
Normal reaction force
Friction
Tension

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25
Q

What is the resultant force

A

The overall force acting upon a body

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26
Q

What is another word for resultant force

A

Net force

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27
Q

What are two examples of non contact forces

A

Gravity
Electrostatic

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28
Q

What is friction

A

Force that opposes motion

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29
Q

Why does friction occur
(2)

A

-Because two surfaces are rubbing against each other
- Neither surface is smooth

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30
Q

Is resultant force vector or scalar

A

Vector

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31
Q

If the resultant force is negative, what does this mean
(2)

A

It is acting in the opposite direction to the objects motion
Thus decelerating them(slowing them down)

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32
Q

What is the relationship formula between an unbalanced force, mass and acceleration

A

F= MA

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33
Q

What is weight

A

The force acting on an object due to gravitational field strength

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34
Q

What is the formula for weight

A

W=Mass x gravitational field strength

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35
Q

What is the stopping distance

A

The thinking distance + the braking distance

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36
Q

What is the braking distance

A

The distance you travel from when the car applies the brake to when the car stops

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37
Q

What is the thinking distance

A

The distance you travel when the driver first sees the hazard to pressing the break

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38
Q

Name 3 factors that can affect thinking distance

A
  • under the influence of drugs or alcohol
  • being tired
    -being distracted
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39
Q

Name 5 factors that can affect braking distance

A
  • icy/wet road
  • driving fast
    -worn tyres
  • mass of vehicle
  • reaction time
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40
Q

As an car speeds up on the road describe the forces of air resistance and weight

A

Air resistance increases
Weight is constant

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41
Q

When something falls, explain why it initially accelerates
(3)

A

Because the resultant force is large
Due to the unbalanced forces
Weight is greater than air resistance

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42
Q

Explain why
Large resultant force = greater the acceleration
(2)

A

Because the forces are unbalanced
so the rate of change of velocity increases

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43
Q

Why is air resistance a contact force

A

Because it is in contact with the air particles

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44
Q

When does an object begin to fall at a steady speed

(In terms of balance/ resultant/ type of forces

A

When the forces are balanced
When there is no resultant force
The air resistance is equal to the weight

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45
Q

What does terminal velocity of 0 mean in terms of resultant forces

A

No resultant force

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46
Q

If there is no resultant force what is the acceleration

A

0

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47
Q

What is the resultant force of an object with uniform acceleration

A

Constant

(Not 0 because then the object wouldn’t be accelerating in the first place)

48
Q

When mass decreases what happens to the acceleration

A

Acceleration increase

49
Q

If the acceleration increase what will the mass be

A

Mass will be less

50
Q

If the resultant force is balanced (so 0) on a moving object
Comment on its velocity

A

Constant velocity

51
Q

When the velocity changes comment on the resultant force

A

There is a resultant force

52
Q

If a stationary object has a resultant force of 0, comment on its velocity

A

It will remain stationary

53
Q

Why do falling objects reach a terminal velocity

A

Because the force of air resistance is able to balance out the force of weight

54
Q

In hooked experiment
What is the independent and dependent variable
And which axis do they go in only in this particular case

A

Independent variable = force
Dependent variable= extension

Force on y axis
Extension on x axis

55
Q

How would you calculate the extension that the spring has stretched to

A

Original length for unstretched spring- length for specific weight

56
Q

What is the formula for elasticity

A

Force directly proportional to spring constant* extension
F~kx

57
Q

What are two things to keep the same in hooked experiment

A

Angle of ruler
Reference point

58
Q

what is elastic deformation

A

When objects return back to original shape when forces are removed

(Rmeber inelastic deformation is when they don’t return back to their original shape)

59
Q

What is the limit of proportionality

A

The point where hooks law is no longer obeyed(where force is no longer directly proportional to extension)

60
Q

What is inelastic deformation

A

When weights are removed but object does not return back to its original state

61
Q

Why will the natural length of the spring be slightly shorter than when you hang it

A

Because the force of weight is slightly pulling it

62
Q

If you have a high spring constant what does that say about the stiffness and why

A

It will be stiffer because it requires more force

63
Q

Explain the difference between mass and weight

A

Mass is the amount of matter in an object
Weight is the force that gravity pulls on an object
Mass in kg, weight in N

64
Q

Why is weight weaker on the moon

A

Because gravity is weaker so the pull is less

65
Q

Why is it important to make fast moving objects even more streamlined

A

Because they produce greater air resistance

66
Q

What are the 4 steps in hooks experiment

A

Measure original length
add a known weight
measure the extension
Repeat for range of loads

67
Q

When you press the breaks what happens to the kinetic energy

A

Energy is transferred to its surroundings

68
Q

As soon as you untie the ropes of a hot air balloon, which has a weight force of 8500 and air resistance force of 9000, what is the immediate weight force

A

8500 because weight is always constant

69
Q

What is Newton’s 1st law of motion

A

Body will stay in its state (stationary or constant), unless a force is act upon it

70
Q

If you add sand bags to a hot air balloon, what happens to the acceleration?

A

Acceleration increases
Because weight forces decrease

71
Q

What are the 4 steps in hooks experiment

A

Measure starting point
Add weights of different masses
Measure the extension
Repeat for reliability

72
Q

When you press the breaks what happens to the kinetic energy

A

Energy is transferred to its surroundings

73
Q

As soon as you untie the ropes of a hot air balloon, which has a weight force of 8500 and air resistance force of 9000, what is the immediate weight force

A

8500 because weight is always constant

74
Q

What is Newton’s 1st law of motion

A

Body will stay in its state (stationary or constant), unless a force is act upon it

75
Q

If you add sand bags to a hot air balloon, what happens to the acceleration?

A

Acceleration increases
Because weight forces decrease

76
Q

What are the 5 steps in hooks experiment

A

Attach a mass loader to clamp and stand
Measure starting point
Add weights of different masses
Measure the extension
Repeat for reliability

77
Q

When you press the breaks what happens to the kinetic energy

A

Energy is transferred to its surroundings

78
Q

As soon as you untie the ropes of a hot air balloon, which has a weight force of 8500 and air resistance force of 9000, what is the immediate weight force

A

8500 because weight is always constant

79
Q

What is Newton’s 1st law of motion

A

Body will stay in its state (stationary or constant), unless a force is act upon it

80
Q

If you release sand from a hot air balloon, what happens to the acceleration?

A

Acceleration increases
Because weight forces decrease

(Forces are more unbalanced)

81
Q

Which feature of a velocity time graph shows acceleration

A

The gradient

82
Q

Definition of displacement

A

Objects overall change in position

83
Q

what is the total distance and the total displacement of a gun shot that travels to the ceiling which has a height of 200m

A

Distance is 400m
Displacement is 0

84
Q

When they ask for the formula of an equation how are you going to give it

A

Full answer in words with equation in symbols

85
Q

What is the benefit of using an air track when investigating motion

A

Can move at a constant speed because air reduces friction

86
Q

Explain a velocity graph of a van moving where the line is straightly diagonal and then the steepness is reduced, then it’s a straight line, in terms of forces (9)

A

the driving force is greater than the force of air resistance
So forces are unbalanced and there is a resultant force
so the van accelerates

the force of air resistance increases
as the speed increases
So acceleration decreases

Force of air resistance is equal to size of driving force
Forces are balanced so there is no acceleration
Van is driving at a constant speed

87
Q

explain how the upward acceleration of a ballon changes during the first few seconds of its flight

A

Speed increases
so air resistance increases,
thus acceleration increases

downwards force increases
So acceleration decrease

88
Q

A velocity time graph is given, where the first 30 seconds is represented as a trapezium, and the last 30 seconds is represented as a trapezium. How would you know if the first 30 seconds had a larger distance or the last 30 seconds (2)

A

Distance is given by area under a graph
The distance with the first 30s is larger because it covers a greater area

89
Q

Suggest two ways of how you can increase the accuracy of measuring the length of the extension

A

1) Use a calliper
2) use a ruler with finer calibrations

90
Q

How can you work out the force of an object if you know the mass

A

W=MG

91
Q

Why does the force exerted by a man on the sledge need to be greater than the force made by acceleration

A

Because friction will produce resistance, so more force is needed to overcome it

92
Q

How can a student increase the quality of his data in hooked experiment

A

Increase the range of loads
Load and unload at different intervals

93
Q

Why do objects at terminal velocity stay at a constant speed

A

They have a resultant force of 0
No acceleration
Forces are balanced
Newton’s second law of motion states that when forces on a moving object are balanced they continue to move at a constant speed

94
Q

For falling objects, why does air resistance increase as velocity increases

A

Because they are colliding with air particles at a faster rate

95
Q

What is the equation for average velocity

A

Total Distance/ total time

96
Q

A skydiver is traveling at terminal velocity and the line on the velocity time graph is horizontal , but then they open a parachute. Explain how the graph looks now

A

There is a short but rapid deceleration, and then it becomes a straight line again
because due to the air resistance of the parachute, the drag force becomes larger than the weight force,
but eventually the weight force is equal to the drag force so the object travels at terminal velocity and the line on the graph become a horizontal straight line

97
Q

Why does speed increase as an object falls

A

Because gravitational force increases due to gravity (gravity is strongest closest to the earth)
And a change in force affects how a moving object falls (newtons

98
Q

Name the four SUVAT equations

A

S= ut + 1/2 at^2
S= (v+u)/2 x t
A= (v-u)/t
v^2=u^2+2as

99
Q

What is instantaneous speed?

A

The speed travelled by an object in a particular moment in time

100
Q

Why could a resultant force be negative

A

It’s is vector quantity
And happens because the resultant force is acting in opposition to the objects motion

101
Q

What is gravitational field strength measured in

A

N/Kg

102
Q

Object A has a higher spring constant than object B.
Explain what this means about the stiffness of the object

A

Object A is stiffer than object B
Because higher spring constant(which is measured in N/M, means that more newtons are required to stretch the object by 1 metre)

103
Q

Three factors that will change the momentum of an object:

A

Change in velocity, so if it accelerates or decelerates
Change in mass
Change in direction

104
Q

Explain why a gun still moves back less than the bullet moves forward, even though every action has an opposite and equal reaction

A

Because of snewtons second law of motion which is F= MA, so the force also depends on the mass and acceleration.
If you rearrange the equation for acceleration,
You will see that the gun has higher mass therefore less acceleration so moves back only a bit
The bullet has less mass therefore higher acceleration so moves back more

105
Q

State the force and momentum equation, and then explain where it is derived from

A

F = (Mv - Mu)/ t

Derived from Defintion of acceleration
Which is a = (v-u)/t
So if you out that into the frost equation and simplify, you would get the force and momentum equation

106
Q

Difference between static friction and sliding friction

A

Static friction is the friction between two objects that are not in motion
Sliding friction is the friction between two objects that’s are in motion

107
Q

Describe ethe relationship between speed and drag in a fluid

A

The fast an object moves through a fluid, the more air resistance it will experience
The slower an object moves through a fluid, the less air resistance it experiences

108
Q

An experiment to investigate acceleration is set up like:
A ramp with a toy car in the end. The ramp is attached to a straight runway. There are two light gates on the ramp. And one at the end of the runway.
Explain how you can investigate acceleration:(6)

A

1)A = (V-U)/t
So initial Velocity is 0 bc the car is at rest.
To find the Final velocity, Let go of the car, and the light gates will measure the time between the second light gate and the third. (Repeat to find an average time)Then measure the distance between the second light gate and the third. Then use S=D/T to work out this velocity.
The Time value will be the time taken between light gate 1 and 2( bc this is when the car was accelerating)
Put values into equation to find acceleration

109
Q

What is the conservation of momentum

A

That the momentum before an event is equal to the momentum after an event, in a closed system

110
Q

State and explain one way in which heavy rain can increase the stopping distance.
Then suggest a way that they could reduce this speed

A

Rain makes the tyres grip less strong, therefore braking distance is increased.
Drive slower

111
Q

If I drop a heavy object and a light object of same size from same height, which will reach a lower terminal velocity and explain

A

(Low terminal velocity means the first one that reaches terminal velocity basically)
The lighter ball, because as it has less weight, it will require less air resistance to balance the weight
And because air resistance increases with velocity, it will take less time for the air resistance of the light ball to equal the air resistance of the heavy ball
(Because the heavy balls velocity will still keep increasing, waiting for the air resistance force to balance it)

112
Q

Elastic behaviour meaning

A

That when the forces are removed from the object that are deforming it, the object will return back to its original shape

113
Q

On a graph if they ask you to find acceleration what will you do
( on a velocity time graph )

A

Use the normal formula change in velocity/ change in time

114
Q

Which energy store of a spring increases when it is stretched

A

The elastic potential

115
Q

A sky diver opens their parachute, and their velocity decreases until they reach a terminal velocity.
Explain these changes in velocity

A

When parachute opens, air resistance is greater than weight,
Thus there is an upwards resultant force
And so a deceleration
And so as THE VELOCITY BEGINS TO DECREASE,the air resistance force will also decrease
So the air resistance force will equal to the weight force
And so there will be no resultant force
And so the diver will fall at a constant speed and have reached terminal velocity

physics (10 decks)

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