Physics (Paper 2) 🔥 Flashcards
(212 cards)
1
Q
(SP8/9)
Energy definition
A
the ability to do work or cause a change
2
Q
Work done definition
A
Energy transferred
3
Q
Equation for work done
A
Force x Distance
4
Q
Work done is measured in
A
Joules
5
Q
Time is measured in
A
Seconds
6
Q
Energy stores/transfers
A
• GPE
• EPE
• Chemical
• Kinetic
• Nuclear
• Electrostatic
• Magnetic
• Thermal
• Sound
7
Q
How is force worked out?
A
Mass x acceleration
8
Q
Contact force definition
A
A force that acts between two touching objects
9
Q
Reaction force definition
A
The force of an object at rest on a surface
10
Q
Air resistance definition
A
the force of an object moving through the air
11
Q
Upthrust definition
A
• Upward force exerted by liquids
• Weight of water displaced
12
Q
Non contact force definition
A
A force acting between 2 objects that do not touch
13
Q
Examples of contact forces
A
Upthrust, friction, reaction force
14
Q
Examples of non contact forces
A
Gravity, magnetism and electrostatic force
15
Q
Scalar tells us the…
A
Magnitude (size) of a force
16
Q
Vector tells us the…
A
magnitude and direction of a force
17
Q
What is Newton’s Third Law of Motion?
A
Whenever 2 bodies interact, the forces they exert on each other are equal and opposite
(in a closed system)
18
Q
Equilibrium definition
A
When forces are balanced or cancel out
19
Q
Friction definition
A
Force between 2 surfaces sliding
20
Q
Resultant force
A
Overall force acting on an object
(aka net force)
21
Q
Net force definition
A
Sum of the forces applied on object (overall force)
22
Q
Moment definition
A
Turning force
23
Q
Moment equation
A
Force x Distance perpendicular to force
24
Q
Clockwise moment is equal to…
A
anti clockwise moment
25
A free body diagram models the
Forces acting on an object
26
Examples of vectors
• Velocity
• Displacement
• (any force eg friction, weight, normal force)
27
Moment is calculated in
Newton metres
28
Equation for Weight
Mass x gravitational field strength (10 N/kg)
29
Examples of scalar quantities
• Temperature
• Energy
• Speed
• Time
30
(SP10)
Electrical circuit definition
a closed path where electrons flow in a wire
31
Series circuit
Only has one pathway or loop
32
Parallel circuit definition
A circuit in which current can flow through on multiple paths
33
Diode definition
A component that only allows current to flow in one direction
34
What is the unit of charge (Q)?
Coulomb (C)
35
What is the unit of current?
Amperes
36
What does LDR stand for?
Light Dependent Resistor
37
What does LDR (Light Dependent Resistor) mean?
Resistor that depends on light intensity. As the light intensity decreases the resistance increases and vice versa
38
The direction of current flow is from..
the positive terminal to the negative terminal of the power supply
39
Current meaning
Rate of the flow of charge
40
Charge =
Current x time
41
Energy transferred equations
voltage (V) x Charge (Q)
or
Voltage (V) x Current (I) x Time (t)
or
Power (P) x Time (t)
42
Voltage meaning
Energy transferred per unit charge
(V = E/Q)
43
What type of circuit are ammeters connected in?
Series
44
What component can only be connected in a parallel circuit?
Voltmeter
45
Voltage equations
V = Current (I) x Resistance (R)
V = Energy transferred (E) / Charge (Q)
V = Power (P) / Current (I)
46
Current is directly proportional to
Voltage
47
Unit for resistance
Ohms
48
Resistance meaning
Opposition to current
49
As resistance increases, what happens to current?
Current decreases
50
How to work out the total resistance in a series circuit?
Adding up all the individual resistances (Rtotal = R1 + R2 + Rn)
51
How to work out the total resistance in parallel circuits?
Reciprocal of each of the resistances added together
(1/Rtotal = 1/R1 + 1/R2 + 1/Rn)
52
Thermistor
Resistor that responds to temperature
53
Ohms law
Current flowing through a conductor is directly proportional to the voltage (V = IR)
54
Power definition
The rate at which energy is transferred per second
55
Unit for power
Watts
56
Equations for power
P = I (Current) x V (Voltage)
P = I² (Current²) x R (Resistance)
P = E (Energy transferred) / T (Time)
57
(SP8) Kinetic energy equation
KE = 0.5 x mass x velocity²
58
Mass is measured in
Kg
59
Weight (and all other forces) is measured in
Newtons
60
How does resistance affect current in filament lamps?
As the current increases the temperature also increases • Increase in temperature increases the resistance • Causes current to increase at slower rate • (I-V graph has S shaped curve through origin)
61
What’s the relationship between voltage and current in diodes?
The current through a diode flows in one direction only • The diode has a very high resistance in the reverse direction so current is unable to flow • (I-V graph slopes upward with nothing shown on bottom side of graph)
62
Relationship between current and voltage in fixed resistors
• Current is directly proportional to voltage • Temperature remains constant • Resistance remains constant • (I-V graph presented as a straight line through origin as it obeys Ohm’s law)
63
AC meaning
Alternating current • Current that changes its direction back and forth
64
DC meaning
• Direct Current
• Current that flows in the same direction (positive terminal to negative terminal)
65
Characteristics of the UK domestic supply
- Supply is AC
- Frequency is 50 Hz
- Voltage is 230 V
66
What power supplies produce direct current?
Cells and batteries
67
Difference between AC voltage and DC voltage
In DC the voltage remains constant whereas in AC the voltage changes between positive and negative
68
When resistors are connected in series the resistance (Increases/decreases) and why ?
Increases
because the sum of resistances of individual resistors is equal to the total resistance
69
When resistors are connected in parallel the resistance (increases/decreases) and why?
Decreases
because the current has more pathways to go through therefore it’s easier for current to flow
70
Frequency meaning
Number of cycles (number of times the current changes direction) each second
71
Why do wires become hotter when an electric current passes through them?
• As current increases, electrons have more energy
• When electrons flow through a wire, they collide with the ions in the wire
• The current here is doing work against the resistance
• This transfers energy to the ions, causing them to vibrate more
• This makes it more difficult for electrons to flow through the wire
• So resistance increases, and current decreases
72
Live wire
Copper wire coated with **brown** plastic • Carries alternating current at 230V
73
Neutral wire
Copper wire coated with **blue** plastic • Completes the circuit and is at 0V
74
Earth wire and its purpose
Copper wire coated in **green and yellow striped** plastic • Used for safety and is at 0V
• It’s connected to a metal case conductor
• Case is kept at same potential difference as Earth’s, so a shock wouldn’t be experienced if it’s touched
75
What’s a fuse and what happens to it during excessive current?
• Connected to the live wire
• Melts during excessive current
• Temperature of the wire increases beyond its melting point causing fuse to melt and break
• The circuit gets broken and no more current can flow through the device
• This prevents a fire
76
As I-V graphs curve what happens to resistance?
It increases
77
How would you reduce unwanted energy transfer through wires?
• By using thicker wires with a lower resistance to minimise heat produced
• Reducing current to reduce collisions
78
Advantages and disadvantages of the heating effect of an electric current
Advantages:
Provides warmth for electric heaters and kettles
Disadvantages:
- Often a form of wasteful energy
- Can lead to overheating and potentially a fire
79
How do LDRs increase in resistance?
When light intensity decreases
80
What happens to the resistance of a thermistor as temperature increases?
It decreases
81
What happens to the resistance of a filament lamp as temperature increases?
It increases
82
Application of LDRs or Thermistors
Used in sensor circuits: eg thermostats which regulates the temperature in heating/cooling systems
83
(SP8) GPE equation
• GPE = mass (kg) x gravitational field strength (N/kg) x vertical height raised (m)
• **mgh**
84
Unlike charges (attract/repel)
Attract
85
Like charges (attract/repel)
Repel
86
The more friction that occurs within a circuit…
The higher the resistance and the less electrons that flow
87
How does an insulator become charged by friction?
When two insulating materials are rubbed together, electrons are transferred creating an imbalance of charge that’s built up
88
Why do insulators not lose its charge?
Electrons can’t be conducted in an insulator
89
Earthing
The removal of excess charge by the movement of electrons
90
What happens during a spark?
The electrons jump between 2 charged objects creating a visible discharge of electricity
91
Static electricity meaning
The build up of charge on insulators
92
Objects normally have a neutral charge overall. Explain why.
Normally, the number of positive protons is equal to the number of negative electrons, so the charges balance each other making the overall charge neutral.
93
How does lightning occur?
• In a storm, clouds move over each other and causes them to become charged as electrons are transferred
• The build up of negative charge in the clouds jump as it attracts to the positive charges on the ground
• It creates a giant spark as the potential difference is large enough to overcome the resistance of the air
94
Why can sparks be dangerous?
They can cause a fire by igniting liquids eg petrol
• Static charge builds up as fuel passes through hose
• When p.d. is too large a spark takes place
• This ignites the fuel
95
Meaning of force
A push or pull acting on an object
96
How does current compare in series and parallel circuits
Current is the same throughout a series circuit but splits in parallel
97
How does voltage compare in series and parallel circuits?
Voltage is split across components in series but is the same throughout parallel circuits
98
Electrical field
A region where an electric charge experiences a force
99
Where are electrical fields weakest on a charged object
At the edges
100
What direction do field lines go in positive and negative objects?
Positive : Outwards
Negative : Inwards
101
How many watts is a MW?
1,000,000 W
102
Charging by induction
When the magnetic field of a charged object induces a charge on a neutral object
103
The closer together the arrows are in field lines…
The stronger the electric field
104
Examples of items that become charged by friction
Polythene rod, cloth and balloons
105
What subatomic particle is transferred to make an object charged?
Electrons, -e
106
Why do materials that gain electrons become negatively charged?
Electrons are negatively charged particles and the imbalance of electrons creates an overall negative charge
107
How do we experience shocks from everyday objects?
When we touch a charged object the excess charge flow through our bodies creating an electric shock
108
How does earthing remove excess charge?
When objects are connected to the ground (through conductors) any excess charge will flow into the ground and neutralise the charge
109
How do insecticide sprayers use static electricity?
• Insecticide is given a charge as it leaves the sprayer • The droplets then repel each other as they have the same charge • This helps it cover a large surface area
110
How is sparking prevented during the refuelling of aeroplanes ?
The use of a metal wire means that the potential difference is the same on the nozzle and plane, as the excess charge gets earthed so there’s no imbalance of electrons
111
How do you calculate efficiency?
Useful energy transferred / Total energy supplied
112
Devise a method a student could use to investigate how resistance changes with potential difference
[Ensure a lamp, voltmeter, variable resistor and ammeter is included in circuit]
• Measure the current using ammeter
• Measure potential difference with voltmeter
• Vary the potential difference
• Calculate the resistance
• Repeat experiment and compare results
113
How do you find resistance on an IV graph?
Draw a tangent to the curve
114
[Topic 12]
What metals do magnets attract?
• Iron
• Cobalt
• Nickel
• Steel
115
In what direction do magnetic field lines flow?
From North to South
116
Where is the magnetic field strongest?
At the poles
117
What is a permanent magnet?
A magnet that produces its own magnetic field
118
What is an induced magnet?
A material that becomes a magnet when placed in a magnetic field
119
Electromagnet meaning
A solenoid with an iron core
120
How would you use plotting compasses to determine magnetic field lines?
• Place compass on paper near magnetic field
• Draw arrow in direction the compass points
• Repeat at different points on paper
• Join the arrows to make complete field line
121
What does a magnetic compass contain?
A small bar magnet pointing in direction of Earth's magnetic field
122
What's a uniform magnetic field?
• One that has the same strength and direction at all points
• Equally spaced apart
123
Evidence for the Earth's core being magentic
In the absence of magnets/magnetic materials, a magnetic compass would always point north as it attracts to core's magnetic field
124
What happens when current flows through a conducting wire?
A magnetic field is produced
125
What is the shape of a magnetic field produced by a current?
• Concentric circles
• Circles get further apart as field weakens further out
126
What represents current going IN and in what direction does the magnetic field
go?
• An X
• Field lines going a clockwise direction
127
What represents current going OUT and in what direction does the magnetic field
gо?
• A dot
• Field lines go in an anti clockwise direction
128
How can we increase the strength of an electromagnet?
• Increase number of turns in coil
• Increase current
• Add an iron core
129
When does the motor effect occur?
When a wire with current flowing though is placed in a magnetic field and experiences a force
130
How does an electric motor work?
• The power supply applies a potential difference across the coil
• A current flows through the coil and a magnetic field is produced from it
• The magnetic feld interacts with the magnetic fleid of the permanent magnets it is perpendicular to
• This creates a rotational effect on the coil
131
Why do the opposing sides of a coil in a dc motor feel a force in opposite directions?
Current is flowing in opposite directions on each side
132
What does a split ring commutator do?
• Reverses the direction of the current every half turn
• Keeps coil rotating continuously
133
Factors affecting the speed at which the coil rotates
• Size of current
• Magnetic field strength
• Number of turns on coil
134
How can we change the direction of rotation of the coil?
• Reverse direction of current
• Reverse direction of magnetic field (poles of magnet)
135
How can we increase the force supplied by the motor?
• Increase the size of current
• Increase magnetic field strength
• Add more turns to coil
136
Why does the coil rotate continuously in a dc motor when there’s current?
• The split ring commutator causes the current to reverse direction
• This reverses the direction forces are acting and so coil continues to rotate
137
Equation for magnetic force on current carrying conductor
F = BIL
Force (N) = Magnetic field strength (T) x Current (A) x Length of conductor in field (m)
138
How can we use Fleming’s left hand rule to determine force? (FBI)
• All 3 fingers must be held perpendicular to each other
• Thumb represents force direction
• 1st finger represents magnetic field direction
• 2nd finger represents current direction
139
Equation linking coil potential difference and number of turns
Vp Np Vs Ns
—— = —— or —— = ——
Vs Ns Vp Np
140
Equation linking potential difference in coil and current in coil
**V**p x **I**p = **V**s x **I**s
141
Equation for force on conductor at right angles to a magnetic field carrying current
F = B x I x L
142
Change in thermal energy equation
△E = mc△T
Thermal energy change (J) = Mass (kg) x Specific heat capacity (J/kg°C x Temperature change (°C)
143
Thermal energy for change of state equation
E = mL
Thermal energy (J) = Mass (kg) x Specific latent heat (J/kg)
144
Elastic Potential Energy equation
E = 1/2kx²
Epe (J) = Spring constant (N/m) x extension (m)
145
Pressure due to column of liquid equation
P = h x ρ x g
Pressure (Pa) = column height (m) x liquid density (kg/m³) x gravitational field strength (N/kg)
146
Pressure/Volume of gases of fixed mass at constant temperature equation
P1 x V1 = P2 x V2
Initial pressure (Pa) x Initial volume (m³) = Final pressure (Pa) x Final volume (m³)
147
How does a positively charged plastic comb pick up pieces of paper?
• A negative charge is induced on the part of paper closest to the comb
• Opposite charges attract
148
Vector drawing tips
• Reaction force always acts at the normal
• Friction acts opposite to movement, along line of movement
• Weight acts downwards from centre of mass
149
Forces acting on skydiver as it moves through air
• Initially, the only force acting on them is their weight, as they have no air resistance
• As they fall, they accelerate, increasing speed and air resistance
• So resultant force decreases
• Therefore acceleration decreases as F = ma (2nd law)
• Eventually weight and air resistance become equal and balanced so there’s no resultant force
150
Forces acting on car
• Thrust is intially opposed by friction
• Air resistance increases, reducing resultant force
• Eventually, thrust is balanced by air resistance and friction, so there’s no resultant force acting
151
How do gears work?
• When a gear is connected to a larger gear, the larger one will turn slower, with more force, in the opposite direction
• Work done by both gears are the same
• To increase power, use a larger secondary gear (to increase distance from pivot and moment)
152
How do levers work?
• They increase the perpendicular distance of the force from the pivot, which decreases the force needed to produce the same moment
• They act as a force multiplier
153
How does lubrication improve efficiency?
• It reduces friction
• So less energy is dissipated (as heat)
154
Danger of providing connection between earth and live wires
• The earth wire is connected to the casing
• If the live wire touches the metal casing, the earth wire also becomes live
• This could lead to an electric shock if touched, as current flows through you to the ground
155
The greater the power rating..
The greater the energy consumption per second
(More energy is used in a given time)
156
What’s the right hand grip rule used for?
Determine the direction of magnetic field using current direction
157
Is the magnetic field **on the outside** of a solenoid strong or weak? And why?
It’s weak because the fields from each turn of coil cancel each other
158
Is the magnetic field **on the inside** of a solenoid strong or weak? And why?
It’s strong because the coils of wire causes the field to align into a giant uniform field
159
The force that a current carrying conductor experiences in a magnetic field is..
Equal and opposite to the force experienced by magnet
160
Producing current on a large scale in the electrical energy generation
• In a thermal power station, water heats up and evaporates to form steam
• The steam is put under pressure and forced into turbine
• This causes the turbine to rotate, which is connected to a massive coil of wire in strong magnetic field
• Current is induced in the coil as it spins through the field
161
What is the Generator Effect and how does it work? (Electromagnetic Induction)
Involves using motion to generate electricity (opposite of motor effect)
• A coil of wire is placed perpendicular to the magnetic field between 2 magnets
• As the wire cuts through the magnetic field, the magnetic field passing through coil changes
• This induces a potential difference across the wire
• This induced voltage produces an induced current (if circuit is complete)
162
When isn’t a current induced in a wire in a magnetic field?
• If it’s stationary
• If the wire is moving parallel to magnetic field
163
Factors affecting size of induced potential difference
• Speed at which coil/magnet is moved
• Number of turns on coil of wire
• Size of coils (larger area = more voltage)
• Strength of magnetic field
164
What factor affects direction of induced potential difference?
Orientation of poles on magnet
165
Why is voltage induced and as a magnet moves into and out of a coil?
To oppose the motion of the magnet
• The induced potential difference always opposes the change that produces it so the coil applies a force to oppose magnet being pushed in
• Therefore the end of the coil closest to magnet will become a North Pole which repels the North Pole of the magnet as it enters
And vice versa, applying a force to oppose magnet being pulled away
so end of coil closest to magnet becomes a South Pole, to attract the magnet’s North Pole
166
How do alternators operate?
• A coil of wire rotates in magnetic field , inducing a potential difference
• The end of the coil is connected to slip rings which cause the current to change direction as it rotates
• Therefore AC is produced
167
How do dynamos operate?
• A coil of wire rotates inside a magnetic field, inducing a potential difference
• A split ring commutator ensures the coil rotates in the same direction, causing the current to flow in the same direction
• This produces DC
168
When the coil is horizontal (flat), at what point is it on a current | time graph and why?
• It’s at its maximum (or also lowest in alternators)
• Because the magnetic field is strongest
169
What does increasing the speed of rotation do to a current | time graph?
Both size and frequency of current increases
170
How does a loudspeaker/headphone operate?
• Alternating current is sent into a loudspeaker
• As the current changes direction, the magnetic field produced changes, causing the cone to vibrate as the force on it is also changing
• This causes vibrations in the air to emit sound
171
How do microphones operate?
• Microphone coil is vibrated by the air
• It oscillates in the changing magnetic field inducing a potential difference and alternating current
• Frequency of alternating current depends on frequency of the sound
172
What effect do loudspeakers use compared to microphones?
Microphones use the generator effect
Loudspeakers and headphones use the motor effect
173
What’s a transformer?
A device that increases or decreases the potential difference of an alternating current, using the generator effect
174
How does a transformer work? (including a step up transformer)
• Alternating current is supplied to the first coil creating a changing magnetic field
• Since the iron core is easily magnetised, the changing magnetic field passes through it
• So there’s now also a changing magnetic field in secondary coil, inducing a potential difference and alternating current
• In a step up transformer, there’ll be more turns on secondary coil
• Therefore voltage increases, as the changing magnetic field cuts through more of the secondary coil, inducing a greater p.d.
(and vice versa for step down transformer)
175
Advantages of high voltage transmission
• Using a large current would mean that the wire heats up, leading to energy loss
• Therefore to transmit the same amount of power, using a higher voltage would would result in a smaller current, because P=IV
• A smaller current means less heat is produced, reducing energy loss and increasing efficiency
176
Disadvantage of high voltage transmission
• High voltages are dangerous
• So near towns, a step down transformer is used to reduce voltage, making it safer
177
Density equation
ρ = m/v
Density (kg/m³) = Mass (kg) / Volume (m³)
178
Movement and arrangement of all solids, liquids and gases
**Solid:**
• Regular arrangement
• Closely packed particles
• Vibrate around a fixed position
**Liquid:**
• Random arrangement
• Particles are still close together
• Particles slide past each other
**Gas:**
• Random arrangement
• Particles are far apart
• Particles move about randomly
179
Comparing the densities in the 3 states of matter
• Solids and liquids have similar densities as the space between particles hasn’t changed much
• Gases have a far lower density as particles have lots of energy to move, increasing the volume of space taken up
180
What happens to mass during a change of state?
Mass is conserved
181
What is sublimation?
When a solid turns into a gas
182
What 2 forms of energy make up the internal energy of a system?
• Kinetic energy (due to their random motion)
• Potential energy (due to particles’ position to each other)
183
Why is there not a chemical change when a state of matter changes state?
The material regains its original properties when reversed
184
What does heating a system do? eg ice cube
• It increases the kinetic energy of its particles, so they vibrate more
• The temperature therefore increases
• Or the system changes state
185
What happens in terms of energy when a substance changes state?
• Potential energy increases, breaking bonds
• Kinetic energy remains the same, (so temperature remains the same)
186
Specific heat capacity
• The amount of energy required to raise the temperature of 1kg of a substance by 1°C
• A higher specific heat capacity means a substance heats / cools down slowly, as it needs more energy
187
Specific latent heat definition
The amount of thermal energy required to change the state of 1kg of a substance **with no change in temperature**
188
2 types of specific latent heat
• Specific latent heat of fusion (solid to liquid and vice versa)
• Specific latent heat of vaporisation (liquid to gas and vice versa)
189
How do we reduce unwanted energy transfers?
• Using thermal insulation to reduce the amount of heat energy transfers
• Eg foam as its a poor thermal conductor
• Or using reflective coatings which reflects IR radiation back into surroundings to maintain colder temperatures
190
Explain the pressure of a gas
• Gas particles move about randomly as they collide with the walls of container
• Increasing the temperature would increase kinetic energy of particles and so they collide with walls more frequently, exerting a higher force on walls (at right angles) (rate of change of momentum increases)
• This increases pressure
191
What is absolute zero?
0 Kelvin or -273°C
• Particles at this temperature have no kinetic energy
TK = TC + 273
192
What happens when gases compress?
• The volume is decreased
• The density of the gas increases so more frequent collisions occur on container walls
• This means pressure increases as there’s a greater force per unit area
193
Pressure is inversely proportional to..
Volume
194
Why does work on a gas increase its temperature?
• Work is done on a gas when it gets compressed
• Doing work increases its internal energy, increasing the average kinetic energy of particles
• This causes temperature to increase
195
What forces are involved during compression of a spring?
• The weight of a mass acting on it and the reaction force
• They act towards each other
196
What forces are involved during the stretching of a hanging spring?
• Weight of a mass on bottom of spring
• Tension in the spring
• These forces act away from each other
197
What forces are acting during bending of a diving board?
• Weight of person
• Reaction force
• These forces act towards each other at different points
198
Difference between elastic and inelastic distortion?
• Elastic distortion occurs when objects return to original shape when stretching force is removed eg rubber bands
• Inelastic distortion occurs when objects remain stretched and do return completely to original shape even when stretching force is removed eg plastic
199
Equation for Hooke’s Law
F = kx
Force (N) = Spring constant (N/m) x Extension (m)
• The extension of a spring is directly proportional to the force applied
200
The higher the spring constant..
The higher the stiffness
201
Interpreting a force extension graph
• The linear relationship is represented by the straight line
• It shows elastic distortion
• The moment it stops is its limit of proportionality
• The graph curves, showing a non linear relationship
202
Fluid meaning
Liquid or gas
203
Why does atmospheric pressure vary with height above Earth’s surface?
• The number of air molecules decreases the higher you go
• So the weight of air above a point decreases, meaning the pressure also decreases
204
What is pressure in a fluid determined by?
Fluid **and** Atmospheric pressure
205
What direction does pressure act in?
All directions (evenly)
206
Why does pressure in fluids increase with depth?
• As depth increases, the mass of liquid above that point increases, so the force produced by that mass also increases
• Force has increased while area has remained constant, so pressure increases
207
Why does pressure in fluids increase with density?
• As density increases there are more particles in a volume of liquid
• So the weight of liquid has increased and therefore the force of liquid above a point is higher
• Since force has increased, pressure also increases
208
Why are objects in a fluid subject to upthrust?
• When an object is submerged in a fluid, it experiences a higher pressure below it than on top of it
• This leads to an upwards force (upthrust)
209
What is upthrust equal to?
The weight of fluid displaced by an object
210
Why does an object float or sink?
• When upthrust is greater than weight of object it’ll float
• If it’s lower, it’ll sink
211
Factors affecting upthrust
• Volume of water and density of water
• They are inversely proportional
212
Why does an object with a higher density than the fluid it’s placed in sink?
• Upthrust = Weight of displaced fluid
• If density of object is high, there wouldn’t be enough volume displaced to produce an upthrust larger than its weight
