Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics > P5- Forces > Flashcards

P5- Forces Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

Do vectors have a magnitude and direction

A

Yes

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

Do scalars have a magnitude and direction

A

No, just a magnitude

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

What are examples of vector quantities

A

+-Force

  • Velocity
  • Displacement
  • Acceleration
  • entum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are examples of scalar quantities

A
  • Speed
  • Distance
  • Mass
  • Temperature
  • Time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a contact force

A

When two objects have to be touching for a force to act

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

What is a non-contact force

A

When the objects do no need to be touching for the force to act

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

What is the difference between weight and mass

A

Mass is the amount of stuff in an object which will be the same anywhere in the universe but weight is the amount of force acting on the object due to gravity

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

What is weight measured in

A

newtons

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

Is mass a force

A

No

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

What is mass measured

A

Kg

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

Mass and weight are_ proportional

A

Directly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Weight =

A

Mass X Gravitational Field Strength

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

Work done (J)=

A

Force (N) X Distance (M)

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

Draw all the forces acting on an object -to-

A

Tip

Tail

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

What is an object called that can go back to it’s original shape after being stretched,bent or compressed

A

Elastic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Extension is _ proportional to force

A

Directly

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

Spring Constant (N/M)=

A

Force ÷ Extension

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

Elastic potential energy=

A

1/2 Spring constant X Extension^2

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

Pressure(Pa) =

A

Force normal to surface(N) ÷Area of that surface(m^2)
Or
Height of the column of liquid (the depth) in m X Gravitational field strength (N/Kg) X Density of the liquid (Kg/m^3)

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

Density is a measure of __ of a substance

A

Compactness

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

What has to be equal for an object to float

A

Upthrust and weight

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

Define atmosphere

A

A layer of air that surrounds the Earth

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

Is distance a scalar or vector

A

Scalar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Is displacement a scalar or vector

A

Vector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Is velocity a vector or scalar

A

Vector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Distance travelled (m)

A

Speed (m/s) X Time (s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Define acceleration

A

How quickly you’re speeding up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Acceleration=

A

Change in velocity (m/s) ÷ Time (s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is deceleration

A

How quickly something slows down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the typical speed of someone walking

A

1.5m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the typical speed of a person running

A

3m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the typical speed of a cyclist

A

6 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the typical speed of a car

A

25 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the typical speed of a train

A

55 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the typical speed of a plane

A

250 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Velocity^2 (m/s) - initial velocity (m/s)

A

2 X Acceleration(m/s^2) X Distance (m)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

True/ False

Drag increases as speed decreases

A

False speed increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is drag

A

The resistance you get in a fluid. Air resistance is a type of drag

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the most important factor by reducing drag

A

Make the object streamline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is terminal velocity

A

The constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What 2 things does terminal velocity depend on

A

Shape and area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What does Newton’s first law state

A

If the resultant force on a stationary object is zero, the object will remain stationary. If the resultant force on a moving object is zero, it’ll just carry on moving at the same velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What was Newton’s second law

A

Acceleration is proportional to the resultant force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Resultant force (N) =

A

Mass (kg) X Acceleration (m/s^2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is inertia

A

The tendency for motion to remain unchanged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is newton’s third law

A

When two objects interact, the forces they exert on each other are equal and opposite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Stopping distance=

A

Thinking distance + breaking distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What two things effect your thinking distance

A
  • Your speed

- Your reaction time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What 4 things effect your breaking

A
  • Your speed
  • The weather or road surface
  • The condition of your tyres
  • How good your brakes are
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Breaking realise on ___ between the brakes and wheels

A

Friction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What can test reaction

A

Ruler drop test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What is conservation of momentum

A

Is a closed system, the total momentum before an event is the same as after the event

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Momentum=

A

Mass X Velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Change in momentum=

A

Force X change in time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Is momentum always concerved

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Is momentum a scalar

A

No- a vector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Momentum is _ within a system unless an external _ acts on the system

A

Conserved

Force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Acceleration is the _ of change of velocity

A

Rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Acceleration=

A

Change in velocity / time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Do all objects have momentum if they have mass and velocity

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What is the average speed of somebody cycling

A

6m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is the average speed of somebody walking

A

1.5m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is the average speed of somebody running

A

3m/s

64
Q

What is the rough equation for m/s to mph

A

m/s= mph ÷ 2

65
Q

What does collision mean

A

Stick together

66
Q

What is a scalar quantity?

A

● A quantity that only has a magnitude
● A quantity that isn’t direction
dependent

67
Q

What is a vector quantity?

A

A quantity that has both a magnitude and

an associated direction

68
Q

How can a vector quantity be drawn and

what does it show?

A 
● As an arrow
● The length of the arrow represents the
magnitude
● The arrow points in the associated
direction
69
Q

What is a force?

A

A push or pull acting on an object due to

an interaction with another object.

70
Q

What are the two categories that all

forces can be split into?

A
  1. Contact forces (objects touching)

2. Non-contact forces (objects separated)

71
Q

Give three examples of contact forces.

A
  1. Friction
  2. Air resistance
  3. Tension
72
Q

Give three examples of non-contact

forces.

A
  1. Gravitational forces
  2. Electrostatic forces
  3. Magnetic forces
73
Q

Is force a vector or a scalar quantity?

A

● Vector
● It has both a magnitude and an
associated direction

74
Q

Give three examples of vector quantities.

A
  1. Velocity
  2. Displacement
  3. Force
75
Q

Give three examples of scalar quantities.

A 
● Temperature
● Time
● Mass
● Speed
● Distance
● Energy
76
Q

What is weight?

A

The force that acts on an object due to

gravity and the object’s mass.

77
Q

What quantities does weight depend on?

A

Weight = mass x gravitational field strength
● The object’s mass
● The gravitational field strength at the
given position in the field

78
Q

What is the unit used for weight?

A

The Newton (N).

79
Q

What is the unit used for gravitational

field strength?

A

N/kg

80
Q

What is meant by an object’s centre of

mass?

A

The single point where an object’s

weight can be considered to act through.

81
Q

What piece of equipment can be used to

measure an object’s weight?

A

A calibrated spring-balance or newtonmeter.

82
Q

What is the name given to the single force that is equivalent to all the other
forces acting on a given object?

A

The resultant force.

83
Q

What does it mean if a force is said to do

‘work’?

A

The force causes an object to be

displaced through a distance.

84
Q

What is the equation used to calculate

work done? Give appropriate units.

A 
Work done = Force x Distance
Work done (Joules), Force (Newtons),
Distance (metres)
85
Q

What distance must be used when

calculating work done?

A

It must be the distance that is moved

along the line of action of the force

86
Q

Under what circumstance is 1 joule of

work done?

A

When a force of 1 Newton causes a

displacement of 1 metre.

87
Q

How many Newton-metres are equal to 1

joule of energy?

A

1 Nm = 1 J

88
Q

How much work is done by the force acting on the

below object over a distance of 5m?

A

10 x 5 = 50 Nm

= 50 J

89
Q

What occurs when work is done against

frictional forces?

A

● A rise in temperature of the object
occurs
● Kinetic energy is converted to heat

90
Q

Why does air resistance slow down a

projectile?

A

● The object does work against the air
resistance
● Kinetic energy is converted in to heat,
slowing down the object

91
Q

Explain the relationship between the
force applied and the extension of an
elastic object.

A

The extension is directly proportional to
the force applied, provided that the limit
of proportionality is not exceeded

92
Q

What is meant by an inelastic (plastic)

deformation?

A

● A deformation which results in the
object being permanently stretched
● The object doesn’t return to its original
shape when the force is removed

93
Q

State the equation relating force, spring
constant and extension. Give appropriate
units.

A

Force = Spring Constant x Extension
Force (N), Spring Constant (N/m)
Extension (m)

94
Q

What type of energy is stored in a spring

when it is stretched?

A

Elastic potential energy.

95
Q

What can extension be replaced with in

the equation for spring force?

A

Compression.

96
Q

What is an alternative name for the

turning effect of a force?

A

A moment.

97
Q

State the equation used to calculate the
moment of a force. Give appropriate
units.

A

Moment of force = Force x Distance

Moment (Nm), Force (N), Distance (m)

98
Q

What distance measurement is used

when calculating a moment?

A

The perpendicular distance from the

pivot to the line of action of the force.

99
Q

If an object is in equilibrium, what can be
said about the moments acting on the
object?

A

The clockwise moments are equal to the

anticlockwise moments.

100
Q

What three parts make up a lever

system?

A
  1. Load
  2. Effort
  3. Pivot
101
Q

How can a lever be used as a force

multiplier?

A

If the distance between the effort and pivot is
greater than the distance between the pivot
and load, the force applied on the load is
greater than the effort force. This is since the
moment on both the effort and load must be
the same.

102
Q

Give an example of when a lever may be

used to multiply a force.

A

A wrench, which has a long handle so that the

force applied by the user is multiplied.

103
Q

What determines the moment of a gear

wheel?

A

The size of the wheel.

104
Q

Describe the moment and speed of a
larger gear being driven by a smaller
gear.

A

The larger wheel will rotate more slowly but

will also produce a larger moment.

105
Q

What is meant by the term ‘fluid’?

A

A liquid or a gas.

106
Q

In any fluid, at what angle do the forces

due to pressure act on a given surface?

A

At right angles (normal to) the surface.

107
Q

State the equation used to calculate

pressure. Give appropriate units.

A

Pressure = Force/Area
Pressure (Pascals), Force (Newtons),
Area (metre²)

108
Q

What happens to the density of the

atmosphere with increasing altitude?

A

The atmosphere becomes less dense as

altitude increases.

109
Q

Explain why atmospheric pressure

decreases with an increase in height.

A

● Pressure is created by collisions of air
molecules
● The quantity of molecules (and so weight)
decreases as the height increases
● This means atmospheric pressure decreases
with an increase of height

110
Q

What is the Earth’s atmosphere?

A

A thin (relative to the magnitude of the
Earth) layer of gas surrounding the
Earth.

111
Q

How does pressure in fluids increase

with depth?

A

As the depth increases, the mass of liquid
above that depth also increases. This means
that the force due to the mass increases.
Since the force has increased whilst the area
has remained constant, the pressure will
increase.

112
Q

Why does pressure in fluids increase

with density?

A

As the density of a fluid increases, the number of
particles in a given volume increases.
Consequently the weight of the fluid is greater.
This means that the force from the fluid above a
certain point is larger. Since the force has
increased, the pressure also increases.

113
Q

What equation shows the magnitude of

pressure in liquids at different depths?

A

Pressure due to a column of liquid(Pa) =
Column height(m) x density(kg/m³) x
gravitational field strength(N/kg)
P = hρg

114
Q

Why are objects in a fluid subject to an

upthrust?

A

When an object is submerged in a fluid, it has a
higher pressure below it than it does above, as there
is more weight above it at the bottom than there is at
the top. This leads to an upwards force called
upthrust. You float or sink depending on whether the
upthrust is more or less than your weight.

115
Q

What is upthrust always equal to?

A

The weight of the fluid that the object

displaces.

116
Q

What factors influence whether an object

will sink or float?

A

● Upthrust
● Weight
● Density of fluid

117
Q

Explain why an object with a density
greater than that of water can never
float.

A

Upthrust is equal to the weight of the displaced
fluid. If the density of the object is high, there
would not be enough volume displaced to
produce an upthrust larger than the object’s
weight. This means that it will sink.

118
Q

Does a distance quantity require a
specific direction? i.e. Is it a scalar or
vector quantity?

A

No specific direction is required so it is a

scalar quantity.

119
Q

If an object moves 3 metres to the left
and then 3 metres back to its initial
position, what is the object’s total
displacement?

A

● The object has zero displacement
● Displacement is a vector quantity so it also
involves direction
● The object starts and ends at the same point

120
Q

State a typical value for the speed of

sound.

A

330 m/s

121
Q

What is a typical value for human

walking speed?

A

1.5 m/s

122
Q

What is a typical value for human running speed?

A

3 m/s

123
Q

What is a typical value for human cycling

speed?

A

6 m/s

124
Q

State the equation linking distance,

speed and time. Give appropriate units.

A

Distance = Speed x Time

Distance (m), Speed (m/s), Time (s)

125
Q

Why can an object travelling at a
constant speed in a circle not have a
constant velocity?

A

● Speed is a scalar quantity
● Velocity is a vector quantity which means it can
only be constant if the direction is constant
● In circular motion, the direction is continuously
changing

126
Q

How can speed be calculated from a

distance-time graph?

A

The speed is equal to the gradient of the

graph.

127
Q

What must be done to calculate speed at
a given time from a distance-time graph
for an accelerating object?

A

● Drawing a tangent to the curve at the
required time
● Calculating the gradient of the tangent

128
Q

State the equation for the average
acceleration of an object. Give
appropriate units.

A

Acceleration = (Change in Velocity)/(Time
Taken)
Acceleration (m/s²), Velocity (m/s), Time (s)

129
Q

How can the distance travelled by an
object be calculated from a velocity-time
graph?

A

It is equal to the area under the graph.

130
Q

Give an approximate value for the acceleration of an
object in free fall under gravity near the Earth’s
surface.

A

9.8 m/s²

131
Q

What can be said about the resultant force acting on

an object when it is falling at terminal velocity?

A

● The resultant force is zero
● When at terminal velocity, the object is
moving at a constant speed and so
isn’t accelerating

132
Q

State Newton’s first law for a stationary

object.

A

If the resultant force on a stationary
object is zero, the object will remain at
rest

133
Q

State Newton’s first law for a moving object.

A

If the resultant force on a moving object
is zero, the object will remain at constant
velocity (same speed in same direction).

134
Q

What can be said about the braking forces and
driving forces when a car is travelling at constant
velocity?

A

The braking forces are equal to the

driving forces.

135
Q

If an object changes direction but
remains at a constant speed, is there a
resultant force?

A

Since there is a change in direction,
there is a change in velocity and so there
must be a resultant force.

136
Q

What is inertia?

A

The tendency of an object to continue in

its state of rest or uniform motion.

137
Q

State the defining equation for Newton’s

Second Law.

A

Resultant force = Mass x Acceleration

F = ma

138
Q

State Newton’s Second Law in words.

A

An object’s acceleration is directly
proportional to the resultant force acting
on it and inversely proportional to its
mass

139
Q

What is inertial mass?

A

● A measure of how difficult it is to
change a given object’s velocity
● The ratio of force over acceleration

140
Q

State Newton’s Third Law.

A

Whenever two objects interact, the
forces that they exert on each other are
always equal and opposite

141
Q

What is the stopping distance of a vehicle equal to?

A

The sum of thinking distance and braking

distance.

142
Q

For a given braking distance, if the
vehicle’s speed is increased, what can
be said about its stopping distance?

A

The stopping distance is increased with

an increase in speed.

143
Q

Give a typical range of values for human reaction

time.

A

0.2 seconds - 0.9 seconds

144
Q

Give three factors which can affect a driver’s

reaction time.

A
  1. Tiredness
  2. Drugs
  3. Alcohol
145
Q

Give two factors which may affect braking distance.

A
  1. Adverse (wet/icy) road conditions

2. Poor tyre/brake conditions

146
Q

Describe the energy transfers that take place when a

car applies its brakes.

A

● Work is done by the friction force between
the brakes and wheel
● Kinetic energy of the wheel is converted to
heat and is dissipated to the surroundings
through the brake discs

147
Q

To stop a car in a given distance, if its velocity is
increased, what must happen to the braking force
applied?

A

The braking force must also be

increased.

148
Q

State two consequences of a vehicle undergoing

very large decelerations.

A
  1. Kinetic energy converted to heat is
    very high causing brakes to overheat
  2. Loss of control of the vehicle
149
Q

State the equation used to calculate an object’s

momentum.

A

Momentum = Mass x Velocity

150
Q

What is the unit used for momentum?

A

kg m/s

kilogram metres per seconds

151
Q

In a closed system, what can be said about the

momentum before and after a collision?

A

The total momentum before is equal to

the total momentum afterwards

152
Q

State an equation linking change in momentum,

force and time.

A

Force x Time = Change in Momentum

F Δt = mΔv

153
Q

What quantity is equal to the force

experienced in a collision?

A

The rate of change of momentum.

154
Q

If an object’s change of momentum is fixed, what is
the only way to reduce the force that the object
experiences?

A

Increase the length of time over which

the change of momentum occurs.

155
Q

Explain how a seatbelt improves a

passenger’s safety during a collision.

A

● Passenger must decelerate from the vehicle’s velocity at impact
to zero, meaning they undergo a fixed change of momentum
● The force they experience is equal to the rate of change of
momentum
● Seatbelts increase the time over which the force is applied,
reducing the rate of change of momentum and therefore
reducing the force experienced

Physics (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions