Physics (Mrs Clarke’s PPT)

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PARTICLE MODEL OF MATTER; REVISION PPT
PARTICLE MODEL OF MATTER; REVISION PPT
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How do you calculate density?
Density (kg/m3) = mass (kg) / volume (m3)
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How do you calculate volume?
Vote = base x length x height
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How do you find the density of a regular solid?
Measure the volume using a ruler and the mass using a balance and then use density equation
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How do you find the volume of an irregular solid?
Use a eureka can to measure volume of the liquid displace and use a balance to get the mass and then use the density equation
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How do you find the density of a liquid?
Use a balance to find the mass of empty cylinder before taking away the mass of both, measuring cylinder to find volume and then use density equation
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What are the properties of a solid?
Fixed volume and shape, cannot be compressed, does not flow
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What are the properties of a liquid?
Fixed volume, no fixed shape, cannot be compressed, flows easily, takes the shape of the container
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What are the properties of a gas?
No fixed volume or shape, can be compressed, flows easily, spreads out to fill the container
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Why do solids have the highest density?
1.They have more particles in the same volume than liquids and gases, 2.Their particles are closer together
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What is the exception?
Solid water (ice) is less dense than water because it has gas trapped
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Why are some solids more dense than others?
Because particles closer together and some have gas in them
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What happens during a change of state?
Changing temperature or pressure of a material, mass is conserved, only volume changes, physical change can be reversed (so it isn’t a chemical change)
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What are the different changes of state called?
Gas->liquid=condensation
Liquid->solid=freeing
Solid->gas=sublimation
Gas->solid=deposition
Solid->liquid=melting
Liquid->gas=evaporation
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What is internal energy?
the energy stored in a system by the atoms and molecules that make up that system
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How do you calculate internal energy?
Internal energy = kinetic energy + potential energy
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What is kinetic energy and potential energy?
KE{due to motion of individual particles}
PE{due to their bonding within and between molecules}
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How do you calculate specific latent heat?
Specific latent heat (J/kg)= energy (J)/ mass (kg)
(Energy is the top of the triangle)
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What is specific latent heat?
The change of energy when 1kg of a substance changes state, temperature doesn’t rise as energy is being used to break forces of attraction been molecules, different for different changes of state
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What are the two types of specific latent heat?
Specific latent heat of fusion (solid-liquid)
Specific latent heat of vaporisation (liquid-gas)
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What is specific heat capacity?
The energy required to raise the temperature of 1kg of a substance by 1 degree Celsius
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How do you calculate specific heat capacity?
Specific heat capacity (J/kg*c)=change in energy (triangleE)/mass(kg) x temperature change (triangleTheta)
C=triangleE/m x triangleTheta
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What are the molecules in gases like?
Molecules in constant random motion (brownian motion)
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What happens when you heat a gas?
When heated more thermal energy added, so move more as more kinetic energy, so greater force on walls on container causing it o expand or pressure inside to increase
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What is the relationship between pressure and volume?
Pressure (pascals, Pa) x volume (m3) = constant
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What happens to a gas when put under a higher pressure?
When a fixed mass are under higher pressure they are forced closer together, so volume decreases, pressure produces a net force to right angles to the wall so it acts evenly in all directions
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What does pV=constant mean?
If the pressure applied to the gas is doubled, the volume halves. p1V1=p2V2
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How does increasing pressure cause a balloon to burst?
Temp of gas increases so particles have more energy, so move faster and collide with walls of the balloon harder, so higher pressure, this causes more force and the balloon bursts.
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How does decreasing the temperature of a balloon affect the pressure?
Temperature of gas decreases so particles have less energy, so move slower and collide with the walls of the balloon with less force, so this leads to a lower pressure and shrivelling
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How does doing work increase the temperature?
You apply a force and transfer energy (work done against force to push pump down), this increases the internal energy which increases the temperature. KE increases -> increasing temperature/thermal energy, pump gets warm
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What is the equation that links pressure and depth?
Pressure(Pa)=height(m)x Density(kg/m3)x Gravitational field strength(N/kg)
P=h(angled p)g
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Why is pressure at the top less than pressure at the bottom of a container of liquid?
Pressure at the bottom is greater than at the top
because there is a greater height,
so there is more weight pushing down per unit area.
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Why does the density of gas atmosphere get lower as you get higher?
The density of gas atmosphere gets lower as you go higher.
As fewer particles less collisions, so less pressure.
At the surface more air molecules collide, in a given time,
with a surface creating air pressure
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ENERGY RESOURCES;
REVISION PPT
ENERGY RESOURCES;
REVISION PPT
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How do you calculate gravitational potential energy?
GPE = m x g x h
Gravitation potential energy= mass x gravitational field strength x height
J = kg x N/kg x m
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What happens to the GPE?
GPE->KE (conservation of energy)
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What is the gravitation field strength on earth?
g=9.81N/kg
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Example exam question;
Object has mass of 50kg is on a cliff 50m high. Calculate GPE.
What is the KE just before it hits the ground?
1. Equation; GPE = m x g x h
2. Rearrange;
3. Numbers; =50 x 9.8 x 50
4. Calculate; =24,500
5. Units; =J
GPE->KE so, 24,500 -> 24,500
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How do you calculate kinetic energy?
KE (J)= 1/2 x m(kg) x v2(m/s)
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Example exam question;
Mass 80kg speed 12m/s, calculate KE
1. Equation; KE = 1/2 x m x v2
2. Rearrange;
3. Numbers; =1/2 x 80 x 12 2
4. Calculate; =5760
5. Units; =J
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Rearrange the KE equation to get velocity?
!NO TRIANGLE LEARN!
Move 1/2 by doing oposite, remove squared y doing oposite
V=KE/ 1/2 x m (all square rooted)
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What is conservation of energy?
In a closed system [nothing can enter/exit] energy ca’t be created or destroyed, it can be transferred usefully, stored or dissipated (spread) to the surroundings
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Example Exam Question;
Object has mass of 5kg and 250J of GPE, calculate velocity just before it hits the ground?
Conservation of energy; so,
GPE=KE, mgh=1/2 x m v 2
1. Equation; GPE =1/2 x m x v2
2. Rearrange; V=GPE/ 1/2 x m SR
3. Numbers; =250/ 1/2 x 5 SR
4. Calculate; 10
5. Units; m/s
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How do you calculate efficiency?
Efficiency (%) = useful/total x 100
The closer to 100% efficient the more efficient and the less energy or power the device wastes, waste energy is transferred into thermal energy
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What is renewable energy?
Give example?
Advantages?
Disadvantages?
Can be replaced eg. Wind, hydroelectric, solar, geothermal, wave, tidal, biofuels
+renewable, no fuel costs, carbon neutral
-noisy, disrupts habitats, not always available, expensive set-up costs, methane gas(animals)
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What is non-renewable energy?
Give example?
Advantages?
Disadvantages?
Can’t be replaced eg. Coal, oil, gas, nuclear
+cheap, lots of energy, ready made, reliable, short start up time, nuclear has no CO2
-non-renewable, pollution-greenhouse + acid rain ->global warming, nuclear produces dangerous waste that’s expensive &healt
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WAVES;
REVISION PPT
WAVES;
REVISION PPT
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What are transverse waves?
The oscillations (vibrations) are perpendicular (90degrees) to the direction of energy transfer
Eg. seismic S-waves, all EM waves
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What are longitudinal waves?
The oscillations (vibrations) of a longitudinal wave are parallel to the direction of energy transfer
Eg. sound waves, ultrasound, seismic P-waves
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What do waves transfer and what is the evidence or this?
Waves transfer energy, not matter, the wave travels and not the medium.
Transverse-water waves, objects bob up and down and don’t move to the edge
Longitudinal-for a tuning fork, you don’t get a vacuum by the side of it
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How do you calculate the velocity of a wave?
Velocity = frequency x wavelength
V = f (lambda)
V= speed the energy is transferred at through the medium
F=number of waves passing a point each second
Lambda= distance from one wave to the next
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What is and how do you calculate time period?
Time period-time for one wave
Time period (s) = 1
Frequency (Hz)
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What is the electromagnetic spectrum?
Long to short wavelength
Low to High frequency
Radio, Micro, Infrared, Visible light, Ultraviolet, X-Rays, Gamma rays
Real Magic Is Very Unusual eXtreme Gift
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What types of waves are EM waves?
What can they travel through?
What do they transfer? And what does this depend on?
EM waves are transverse waves, they can be absorbed or reflected, they can travel through a vacuum, do not transfer matter, they transfer energy to absorber, energy transfer depends on wavelength of wave, the energy of the wave increases and the wave leng
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How are EM waves produced?
Changes in atoms and their nuclei, atoms absorb energy causing electrons to move to higher energy levels, when it falls back down EM waves are emitted, large no. Of changes can happen which means large range of EM frequencies
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What are the uses and dangers of Gamma rays?
+Treating cancer, sterilisation
-Cell mutation(cancer)
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What are the uses and dangers of X-rays?
+medical
-cell mutation(cancer)
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What are the uses and dangers of Ultra violet?
+sun tanning
-skin cancer
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What are the uses and dangers of Visible light?
+seeing things, fibre optic cables
-none (unless you look at the sun)
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What are the uses and dangers of Infra red?
+remote controls, heat transfer
-sunburn
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What are the uses and dangers of Microwaves?
+satellites, phones
-very few
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What are the uses and dangers of Radio waves?
+communications
-very few
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What is radiation?
What does it depend on?
Radiation does is measured in units called “sieverts” (Sv)
Depends on ^the amount absorbed ^the type of radiation ^type of body tissue
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How are radio waves used in communication?
SHORT radio waves reflect off the ionosphere, little absorption
LONG radio waves bend (diffract) around the earth, little absorption
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How are radio waves used as carrier waves to send signals?
Produced in a transmitter using oscillations->the wave is transmitted through the air->radio absorbs wave turning it back into an electrical signal, the oscillating wave induces an oscillating electrical signal
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What are the visible light wavelength?
Red-0.0000007m to Blue 0.0000004m
Each color has its own narrow band of wavelengths and frequencies
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What do filters do?
Filters transmit certain wavelengths (colours) and absorb all the others
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What affects the color of an object?
The colour of an object appears depends on the colours of light it reflects. The object will absorb the other colours
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What does transparent mean, give examples of transparent materials?
What does translucent mean, give examples of translucent materials?
-let all light through{clear glass}
-let light through but absorbs some of it{frosted glass}
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Give two sources of infrared radiation?
1. The sun
2. Inside a nucleus of an atom
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Why does everything have IR radiation?
All objects have atoms so everything emits and
absorbs radiation, in particular infrared (IR).
The hotter the body, the more IR radiation it
radiates every second.
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How does IR affect temperature?
(THIS INCLUDES EARTH
Temperature is a balance between the amount
absorbed and the amount emitted:- Emit more than absorb = decrease in temp
Emit less than absorb = increase in temp
If temp constant the object is emitting the same as it’s absorbing
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What is a black body?
A body that absorbs all
the of the EM-Radiation that hits it.It doesn’t reflect or transmit any radiation – it simply
absorbs everything. as every object also emits radiation, it follows that a perfect blackbody would also be the best emitter.
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How does temperature intensity affect it?
1) Intensity – how much energy transferred per second
- Hotter = higher intensity of emitted wavelengths
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How is the distribution of wavelengths affected by temperature?
2) Distribution of wavelengths
- Hotter = peak wavelength decreases so has more
short wavelength emissions than cooler objects
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What could happen to a wave when it hits a boundary?
It can be @reflected
@refracted though the material
@absorbed
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What is the law of reflection?
For plain mirrors (smooth, shiny surfaces)
ANGLE OF INCIDENCE = ANGLE OF REFLECTION
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How does density affect refraction?
The ore dense the material the more the wave slows down and the more it bends towards the normal
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What is the ray called that leaves the other side in refraction?
The emergent ray
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How do you describe an image?
Diminished/magnified
Upright/inverted
Real/virtual
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How do you calculate magnification?
Magnification= image height/ object height
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What are convex lenes?
Rays of light are refracted inwards and meet at the focus, f
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What are concave lenses?
Rays of light are refracted outwards
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What is a real image ?
What is a virtual image ?
Real image can be seen on a screen
Virtual image is always formed, you can’t project it onto a screen
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How do you draw a convex lens diagram?
Straight horizontal then down through focal point, straight through x, down through focal point till crosses y axis then straight horizontal across, image is where all lines cross
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How do you draw concave lens diagrams?
If the lines don’t meet them where the first line crosses the y axis draw a diagonal line to the focal point on the same side and where that line crosses the line that goes through the x is where the virtual image is
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How are sound wave produced?
All sound waves are caused by particles vibrating so they can travel in solid, liquids and gases. The closer the art es are the faster the wave speed. Frequency stays the same, wavelength increases (v=f x LAMBDA)
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What types of wave are sound waves?
What can travel through?
Sound waves are longitudinal waves (energy travels in same direction as the wave). Can travel through solids, liquids and gases but not vacuums
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How do we hear sound waves?
An object makes a sound by vibrating, vibrations pass through air making air molecules vibrate, vibrations picked up by human ears[20Hz-20,000Hz], the ear then sends a message to the brain
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How do ears/microphones detect sound waves?
Sound waves make air particles vibrate and they vibrate the ear drum and bones/diaphragm, the vibration produces electrical signals carried by the auditory nerve/a wire to the brain/speaker which converts it to signals
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How are sound waves used for echo sounding?
High frequency sound waves are reflected
from an object to measure the distance to
that object.
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What is ultrasound?
above 20,000Hz, Waves are partly reflected at the boundary as they pass from one medium to another, time taken for these reflections can be used to measure depth of the reflecting surface, this information is used to build up picture object
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What are seismic P-waves?
1) Longitudinal so cause the ground to move up
and down
2) Pass through solids and liquids
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What are seismic S-waves?
1) Transverse so cause the ground to move from
right to left
2) Can’t travel through liquids
3) Slower than P waves
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How do we know about p and S waves?
S waves will only travel
through a solid, They can’t
travel through liquids. A mantle- has the properties of a solid but it can also flow. P waves can travel through liquids and solids. A core- made of molten nickel and iron. Outer part liquid and inner
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What is a scalar?
Give examples
Magnitude (size) only
Eg. distance, mass, speed, time, temperature
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What is a vector?
Give examples
Magnitude and direction
Eg. Acceleration, force, velocity, displacement, momentum
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What is a contact force?
Give examples
-act on touching
Eg. Upthrust, air/water resistance, friction, tension, normal, weight
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What is a non-contact force?
Give examples
-act at a distance
Eg. Gravity, magnetic, electrostatic, nuclear
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What is mass?
Mass measures how much ‘stuff’ there is inside an object. Doesn’t change
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What is weight?
Weight is the force acting on that stuff due to the force of gravity from the Earth. Can change
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How do you calculate weight?
W = mg
Weight = mass x gravitational field strength
(N) = (kg) x (N/kg)
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What is gravitational field strength?
Gravitational field strength (g) • Causes acceleration towards the ground (“due to gravity”)
• On Earth is 9.81 N/kg, but different planets will have a different value of g, depending on the mass of the planet.
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What is the rule for interacting pairs?
“Every action has an equal and opposite reaction”
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What is resultant force?
Determines acceleration and direction of motion, overall effect of forces acting in line, in the same direction add, opposing direction subtract
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Card 4

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