forces/ motion Flashcards
1
Q
What are the units for gravitational field strength
A
N/Kg
2
Q
How many Newton’s is 1 kg
A
10 N
3
Q
What are the standard units for mass
A
Kg
4
Q
What are the units for momentum
A
Kg m/s
(Kilograms metre per second)
5
Q
What are the units for a moment
A
Nm
(Newton metre)
6
Q
What is the formula for speed in terms of notation
A
V=S/T
7
Q
How would you convert from m/s to km/hr
A
1) divide by 1000
2) multiply by 3600
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
9
Q
Definition of displacement
A
Distance travelled in a particular direction
10
Q
What is a vector quantity
A
Has a magnitude and direction
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
12
Q
How can you make human error more reliable
A
Repeat a few time
- and make an average value
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
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
15
Q
What does a curve represent on a distance time graph
A
Change in speed
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)
17
Q
What is the definition of acceleration
A
The rate of change of velocity
18
Q
How is it possible to accelerate without changing your speed
A
Because you can change your direction
19
Q
How can you find average velocity on a graph
A
Half way between the final and initial velocity
20
Q
What is the equation for displacement
A
S = v+u/2 x t
21
Q
What is the equation for final velocity
A
V=u +at
(Final Velocity= Initla velocity + acceleration * time
22
Q
What are three things that a force can change
A
Speed
Shape
Direction
23
Q
If an object accelerates does the air resistance increase or decrease
A
Increase
24
Q
Give 5 examples of contact forces
A
Air resistance
Upthrust
Normal reaction force
Friction
Tension
25
What is the resultant force
The overall force acting upon a body
26
What is another word for resultant force
Net force
27
What are two examples of non contact forces
Gravity
Electrostatic
28
What is friction
Force that opposes motion
29
Why does friction occur
(2)
-Because two surfaces are rubbing against each other
- Neither surface is smooth
30
Is resultant force vector or scalar
Vector
31
If the resultant force is negative, what does this mean
(2)
It is acting in the opposite direction to the objects motion
Thus decelerating them(slowing them down)
32
What is the relationship formula between an unbalanced force, mass and acceleration
F= MA
33
What is weight
The force acting on an object due to gravitational field strength
34
What is the formula for weight
W=Mass x gravitational field strength
35
What is the stopping distance
The thinking distance + the braking distance
36
What is the braking distance
The distance you travel from when the car applies the brake to when the car stops
37
What is the thinking distance
The distance you travel when the driver first sees the hazard to pressing the break
38
Name 3 factors that can affect thinking distance
- under the influence of drugs or alcohol
- being tired
-being distracted
39
Name 5 factors that can affect braking distance
- icy/wet road
- driving fast
-worn tyres
- mass of vehicle
- reaction time
40
As an car speeds up on the road describe the forces of air resistance and weight
Air resistance increases
Weight is constant
41
When something falls, explain why it initially accelerates
(3)
Because the resultant force is large
Due to the unbalanced forces
Weight is greater than air resistance
42
Explain why
Large resultant force = greater the acceleration
(2)
Because the forces are unbalanced
so the rate of change of velocity increases
43
Why is air resistance a contact force
Because it is in contact with the air particles
44
When does an object begin to fall at a steady speed
(In terms of balance/ resultant/ type of forces
When the forces are balanced
When there is no resultant force
The air resistance is equal to the weight
45
What does terminal velocity of 0 mean in terms of resultant forces
No resultant force
46
If there is no resultant force what is the acceleration
0
47
What is the resultant force of an object with uniform acceleration
Constant
(Not 0 because then the object wouldn’t be accelerating in the first place)
48
When mass decreases what happens to the acceleration
Acceleration increase
49
If the acceleration increase what will the mass be
Mass will be less
50
If the resultant force is balanced (so 0) on a moving object
Comment on its velocity
Constant velocity
51
When the velocity changes comment on the resultant force
There is a resultant force
52
If a stationary object has a resultant force of 0, comment on its velocity
It will remain stationary
53
Why do falling objects reach a terminal velocity
Because the force of air resistance is able to balance out the force of weight
54
In hooked experiment
What is the independent and dependent variable
And which axis do they go in only in this particular case
Independent variable = force
Dependent variable= extension
Force on y axis
Extension on x axis
55
How would you calculate the extension that the spring has stretched to
Original length for unstretched spring- length for specific weight
56
What is the formula for elasticity
Force directly proportional to spring constant* extension
F~kx
57
What are two things to keep the same in hooked experiment
Angle of ruler
Reference point
58
what is elastic deformation
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
What is the limit of proportionality
The point where hooks law is no longer obeyed(where force is no longer directly proportional to extension)
60
What is inelastic deformation
When weights are removed but object does not return back to its original state
61
Why will the natural length of the spring be slightly shorter than when you hang it
Because the force of weight is slightly pulling it
62
If you have a high spring constant what does that say about the stiffness and why
It will be stiffer because it requires more force
63
Explain the difference between mass and weight
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
Why is weight weaker on the moon
Because gravity is weaker so the pull is less
65
Why is it important to make fast moving objects even more streamlined
Because they produce greater air resistance
66
What are the 4 steps in hooks experiment
Measure original length
add a known weight
measure the extension
Repeat for range of loads
67
When you press the breaks what happens to the kinetic energy
Energy is transferred to its surroundings
68
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
8500 because weight is always constant
69
What is Newton’s 1st law of motion
Body will stay in its state (stationary or constant), unless a force is act upon it
70
If you add sand bags to a hot air balloon, what happens to the acceleration?
Acceleration increases
Because weight forces decrease
71
What are the 4 steps in hooks experiment
Measure starting point
Add weights of different masses
Measure the extension
Repeat for reliability
72
When you press the breaks what happens to the kinetic energy
Energy is transferred to its surroundings
73
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
8500 because weight is always constant
74
What is Newton’s 1st law of motion
Body will stay in its state (stationary or constant), unless a force is act upon it
75
If you add sand bags to a hot air balloon, what happens to the acceleration?
Acceleration increases
Because weight forces decrease
76
What are the 5 steps in hooks experiment
Attach a mass loader to clamp and stand
Measure starting point
Add weights of different masses
Measure the extension
Repeat for reliability
77
When you press the breaks what happens to the kinetic energy
Energy is transferred to its surroundings
78
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
8500 because weight is always constant
79
What is Newton’s 1st law of motion
Body will stay in its state (stationary or constant), unless a force is act upon it
80
If you release sand from a hot air balloon, what happens to the acceleration?
Acceleration increases
Because weight forces decrease
(Forces are more unbalanced)
81
Which feature of a velocity time graph shows acceleration
The gradient
82
Definition of displacement
Objects overall change in position
83
what is the total distance and the total displacement of a gun shot that travels to the ceiling which has a height of 200m
Distance is 400m
Displacement is 0
84
When they ask for the formula of an equation how are you going to give it
Full answer in words with equation in symbols
85
What is the benefit of using an air track when investigating motion
Can move at a constant speed because air reduces friction
86
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)
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
explain how the upward acceleration of a ballon changes during the first few seconds of its flight
Speed increases
so air resistance increases,
thus acceleration increases
downwards force increases
So acceleration decrease
88
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)
Distance is given by area under a graph
The distance with the first 30s is larger because it covers a greater area
89
Suggest two ways of how you can increase the accuracy of measuring the length of the extension
1) Use a calliper
2) use a ruler with finer calibrations
90
How can you work out the force of an object if you know the mass
W=MG
91
Why does the force exerted by a man on the sledge need to be greater than the force made by acceleration
Because friction will produce resistance, so more force is needed to overcome it
92
How can a student increase the quality of his data in hooked experiment
Increase the range of loads
Load and unload at different intervals
93
Why do objects at terminal velocity stay at a constant speed
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
For falling objects, why does air resistance increase as velocity increases
Because they are colliding with air particles at a faster rate
95
What is the equation for average velocity
Total Distance/ total time
96
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
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
Why does speed increase as an object falls
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
Name the four SUVAT equations
S= ut + 1/2 at^2
S= (v+u)/2 x t
A= (v-u)/t
v^2=u^2+2as
99
What is instantaneous speed?
The speed travelled by an object in a particular moment in time
100
Why could a resultant force be negative
It’s is vector quantity
And happens because the resultant force is acting in opposition to the objects motion
101
What is gravitational field strength measured in
N/Kg
102
Object A has a higher spring constant than object B.
Explain what this means about the stiffness of the object
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
Three factors that will change the momentum of an object:
Change in velocity, so if it accelerates or decelerates
Change in mass
Change in direction
104
Explain why a gun still moves back less than the bullet moves forward, even though every action has an opposite and equal reaction
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
State the force and momentum equation, and then explain where it is derived from
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
Difference between static friction and sliding friction
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
Describe ethe relationship between speed and drag in a fluid
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
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)
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
What is the conservation of momentum
That the momentum before an event is equal to the momentum after an event, in a closed system
110
State and explain one way in which heavy rain can increase the stopping distance.
Then suggest a way that they could reduce this speed
Rain makes the tyres grip less strong, therefore braking distance is increased.
Drive slower
111
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
(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
Elastic behaviour meaning
That when the forces are removed from the object that are deforming it, the object will return back to its original shape
113
On a graph if they ask you to find acceleration what will you do
( on a velocity time graph )
Use the normal formula change in velocity/ change in time
114
Which energy store of a spring increases when it is stretched
The elastic potential
115
A sky diver opens their parachute, and their velocity decreases until they reach a terminal velocity.
Explain these changes in velocity
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
