Forces- Physics Paper 2 Flashcards
1
Q
What does a vector quantity have?
A
A magnitude and a direction
2
Q
What does a scalar quantity have?
A
Just a magnitude
3
Q
What are examples of vector quantities?
A
force, velocity, displacement, acceleration, momentum
4
Q
What are examples of scalar quantities?
A
speed, distance, mass, temperature ,time
5
Q
What is a force?
A
A push or a pull that acts on an object
6
Q
What is the unit of force?
A
Newtons
7
Q
What’s a Contact force ?
A
a force that acts between two objects that are physically touching each other.
8
Q
What’s a non contact force?
A
forces that act between two objects that are not physically touching each other.
9
Q
What are examples of contact forces?
A
Reaction force, Tension, Friction, Air resistance
10
Q
What are examples of non-contact forces?
A
Magnetic force, Electrostatic force, gravity
11
Q
What is an interaction pair?
A
A pair of forces that are equal and opposite and act on 2 interacting objects
12
Q
What is weight?
A
The force acting on an object due to gravity
13
Q
What is mass?
A
The amount of matter in an object
14
Q
What is weight measured in?
A
Newtons
15
Q
What is the centre of mass?
A
The point at which the whole mass of an object is concentrated
16
Q
How do you measure weight?
A
Using a newton meter
17
Q
What is the equation for weight?
A
Weight = mass X gravitational field strength
18
Q
What is the equation for work done?
A
Work done = force X distance moved in the direction of the force
19
Q
What is the resultant force?
A
The sum of all the forces acting on an object overall
20
Q
What does a free body diagram show?
A
the forces acting on an object
21
Q
What do the arrows on the free body diagram represent?
A
The different forces
22
Q
What do the direction of the arrows on a free body diagram show?
A
The direction of the forces
23
Q
What do the lengths of the arrows on a free body diagram represent?
A
The size/magnitudes of the forces
24
Q
What happens if all the forces acting on an object give a resultant force of 0?
A
The forces are balanced and the object is in equilibrium
25
What is meant by resolving a force?
splitting the force into 2 component forces that are at right angles to each other. The combination of the 2 forces has the same effect as the original single force.
26
What is work done?
The energy transferred when a force moves an object through a distance
27
What is elastic deformation?
When an object can go back to its original shape and length after the force has been removed
28
What is inelastic deformation?
When an object doesn't return back to its original shape and length when the force has been removed
29
What are objects that can be elastically deformed called?
Elastic objects
30
What is the extension of a stretched spring directly proportional to?
The load of the force applied
31
What is Hooke's law?
force = spring constant × extension
32
What is the Limit of proportionality?
The limit of proportionality refers to the point beyond which Hooke's law is no longer true when stretching a material. The elastic limit of a material is the furthest point it can be stretched or deformed while being able to return to its previous shape.
33
What happens once a material has gone past its elastic limit?
its deformation is said to be inelastic.
34
The higher the spring constant....
the stiffer the spring
35
What is a moment?
The turning effect of a force
36
What is the equation for a moment?
moment of a force = force × perpendicular distance from the line of action of the force
37
What is a moment measured in?
newton-metres (Nm)
38
What do levers do?
They make it easier for us to do work i.e lift an object
39
Why do levers mean less force is needed to get to the same moment?
Because levers increase the distance from which the force is applied
40
If an object is balanced, the total clockwise moment about a pivot is equal to...
the total anticlockwise moment about that pivot.
41
What does a lever consist of?
a pivot, an effort, a load
42
Why are levers force multipliers?
Because they increase the effect of the force
43
What are gears?
wheels with toothed edges that rotate on an axle or shaft.
44
Will a larger gear turn slower than a smaller gear?
Yes
45
What happens when 2 gears meet?
the teeth must both move in the same direction
46
The forces acting on the teeth of gears are identical but their what are different?
Their moments
47
If the driven gear is made larger it will rotate more slowly but with a greater or smaller moment?
a greater moment
48
If the driven gear is made smaller it will rotate more quickly but with a greater or smaller moment?
smaller
49
What is pressure?
Force per unit area
50
What is a fluid?
Substances that can 'flow' because their particles are able to move around
51
What do fluids include?
Liquids and gases
52
What is the equation for pressure?
pressure = force / area
53
What is pressure measured in?
pascals
54
What is the equation for pressure in a liquid?
pressure = height of column × density of the liquid × gravitational field strength
55
What affects the pressure in a liquid?
The density of the liquid and the depth of the liquid
56
If a liquid becomes very dense, what will happen to the pressure?
The pressure will increase.
57
Why does liquid pressure increase with depth?
Because as the depth increases, the number of particles above that point increases. The weight of these particles adds to the pressure experienced a that point so the liquid pressure increases with depth.
58
What is the atmosphere?
The layer of air that surrounds the earth
59
What is atmospheric pressure created by?
air molecules colliding with a surface
60
What happens to atmospheric pressure when altitude increases?
Atmospheric pressure decreases
61
What 2 factors cause atmospheric pressure to decrease when altitude increases?
Density, and how much air there is above a certain point
62
Why does density cause atmospheric pressure to decrease when altitude increases?
Because as altitude increases, the atmosphere gets less dense. This means that there air fewer air molecules that are able to collide with a surface, which in turn means a lower atmospheric pressure.
63
Why does how much air there is above a certain point cause atmospheric pressure to decrease?
Because an increasing altitude means fewer air molecules above a surface. This means that the weight of the air above, which contributes to atmospheric pressure, decreases.
64
What is the upthrust?
The upward force exerted by a liquid or a gas on an object floating in it
65
What is the upthrust equal to?
The weight of the fluid that has been displaced by the object
66
What happens if the upthrust of an object is equal to or larger than the object's weight?
The force balances and the object floats
67
What happens when the upthrust is less than the weight of the object?
The object will sink
68
Why does an object that is less dense than the fluid it's placed in float?
Because the object weighs less than the equivalent volume of fluid. This means that it displaces a volume of fluid that is equal to its weight before it can become completely submerged. At this point, the upthrust is equal to the object's weight so the object floats.
69
Why does an object that is denser than the fluid it's placed in float?
Because the object weighs more than the equivalent volume of fluid. This means that it is unable to displace enough fluid to equal its weight. As its weight is larger than the upthrust, the object sinks.
70
What type of quantity is distance?
A scalar quantity
71
What type of quantity is displacement?
A vector quantity
72
What does displacement measure?
The distance and direction in a straight line from an object's starting starting point to finishing point.
73
What type of quantity is speed?
A scalar quantity
74
What type of quantity is velocity?
A vector quantity
75
What speed does an object moving in a circle have?
A constant speed
76
What happens to the direction of an object moving in a circle?
It always changes
77
What can affect the speed something travels at?
age
terrain
fitness
distance travelled
78
What is speed?
Speed is the rate of change of distance - it is the distance travelled per unit time.
79
What is the speed of walking?
1.5 m/s
80
What is the speed of running?
3 m/s
81
What is the speed of cycling?
6 m/s
82
What is the speed of a car ?
13 m/s - 30m/s
83
What is the speed of a train?
50 m/s
84
What is the speed of an aeroplane?
250 m/s
85
What is the acceleration?
How quickly the velocity is changing
86
How can acceleration be calculated?
the change in velocity/ time taken
87
What is the equation for uniform acceleration?
final velocity squared - initial velocity squared = 2 X acceleration X distance
88
What is the gradient of a distance-time graph equal to?
The speed
89
The steeper a distance-time graph...
the faster it's going
90
What goes on the horizontal axis of a velocity-time graph?
The time in seconds
91
What goes on the vertical axis of a velocity-time graph?
The velocity in m/s
92
What does the gradient of a velocity-time graph tell you?
The acceleration of the object
93
What are the 2 main ways of changing a vehicle to increase its top speed?
1) Reducing drag by altering the shape of the vehicle to make it more streamlined.
2) Increasing the power of the vehicle's engine so that the driving force becomes larger and so the drag force on the vehicle will equal the driving force at a higher speed.
94
What is terminal velocity?
the decrease in the speed of an object till it reaches a steady velocity
95
What are the 3 stages of falling?
1) at the start, the object accelerates downwards due to the force of gravity
2) as the object's speed increases, frictional forces such as air resistance or drag increase
3) at terminal velocity, the weight of the object due to gravity is balanced by the frictional forces, and the resultant force is zero
96
What factors affect terminal velocity?
the objects shape and the objects area
97
What is Newton's first law?
an object remains in the same state of motion unless a resultant force acts on it.
98
What happens when the resultant force on a stationary object is zero?
The object will remain stationary
99
,
.
100
What different forms can changing velocity take place in?
starting, stopping, changing direction, speeding up, slowing down
101
What is inertia?
When an object will remain stationary , or continue at the same velocity, unless a resultant force is applied
102
What is Newton's second law?
The acceleration of an object is directly proportional to the resultant force acting on the object and inversely proportional to the mass of the object.
103
What is the equation for resultant force?
Resultant force = mass X acceleration
104
What is acceleration measured in?
m/s^2
105
What is the equation for inertial mass?
inertial mass = resultant force/ acceleration
106
What is Newton's third law?
whenever two objects interact, they exert equal and opposite forces on each other.
107
If you push a shopping trolley, what does the shopping trolley do to you?
Push back against you, just as hard
108
What is the equation for stopping distance?
stopping distance = thinking distance + braking distance
109
What is the thinking distance?
thinking distance is the distance a vehicle travels in the time it takes for the driver to apply the brakes after realising they need to stop
110
What is the braking distance?
braking distance is the distance a vehicle travels in the time after the driver has applied the brake
111
What factors affect the thinking distance?
How fast you're going and how quick you are to respond
112
What affects the braking distance?
How good your brakes are, how good the tyres are, how fast you're going, how good the grip is
113
What is the correlation between speed and thinking distance?
They're directly proportional
114
.
.
115
What is momentum?
A property of moving objects
116
What quantity is momentum?
a vector quantity - this means it has both a magnitude and an associated direction.
117
How do you calculate momentum?
momentum = mass X velocity
118
What are the units of momentum?
kg m/s
119
What are the units of velocity?
m/s
120
What is the conservation of momentum?
The idea that in a closed system, the momentum before an event is the same as the momentum after an event
121
What is the equation for changes in momentum?
force = change in momentum/change in time
122
What decreases the rate of change of momentum, which decreases the force of the collision on any people within the car?
Crumple zones, seat belts and air bags
123
What is the force normal?
the force that particles exert at right angles to a surface
124
Where is pressure the highest in the sea?
At the bottom because there's more water above the diver and the weight of the water on the diver is higher
125
What is the speed of sound in air?
330 m/s
126
Do objects that are not moving having momentum?
No, only objects that are moving
