All Of Physics

What is a Star

A large and hot enough body for nuclear fusion to take place

Nuclear Energy is released from it as UV, Visible and Infared radiation

Made up of Hydrogen and Helium

What is a planet

Something that orbits the sun

Is large enough to be spherical

The largest object in its orbit

Order of planets and where the asteriod belt is

Mercury,Venus,Earth,Mars,|||Asteriod belt|||, Jupiter, Saturn, Uranus, Neptune

Name the rocky planets

Mercury, Venus, Earth, Mars

Name the Gas Giants

Jupiter, Saturn, Uranus, Neptune

What is a moon

an object that orbits a planet

What is an asteroid

Large chunk of rock 1km-1000km

Mostly in the asteroid belt

What is a Comet

Made of Ice and dust in a few key areas

Orbits the sun in an elliptical orbit

What is a dwarf planet?

An object that Orbits the Sun

Large enough to be spherical

Shares orbit with other dwarf planets/asteroids

Examples of dwarf planets

Pluto

Ceres

Makemake

Haumena

Eris

What is an artificial salelite

Man-made objects in orbit around

-Earth

-Other planets/moons

-Sun

What keeps the planets in an almost circular orbit around the Sun

The gravitational interaction between the planets and the Sun.

Diagram in circular motion where the gravity/weight is acting and where the velocity is acting

Why do planets closer to the sun have a shorter orbital period

Explain how for a stable orbit, the speed must change if the radius changes

Stronger Gravity at Smaller Radii: As an object gets closer to the central body (smaller orbital radius), the gravitational force pulling it inward becomes significantly stronger.

Higher Speed Needed for Balance: To maintain a stable orbit closer to the center and prevent being pulled inward by this stronger gravitational pull, the planet must move faster so its centripetal acceleration matches the higher gravitational acceleration.

IF the orbital speed increases what must happen orbital radius visa versa

If orbital speed increases, the orbital radius must decrease to remain stable.

If orbital speed decreases, the orbital radius must increase to remain stable.

What was the solar system formed from

Dust and gas drawn together by gravity

Explain how doing work on a gas can increase its temperature

Doing work on a gas transfers energy to its particles during collisions with a moving boundary or gravitational collapse, which increases their average kinetic energy and speed. Because temperature is a measure of the average kinetic energy of gas particles, this increased motion results in a rise in temperature.

How was the Sun formed

Gravitational Collapse: A nebula, mainly containing hydrogen, was pulled together by gravity. As it collapsed, the particles moved faster and collided more often, heating up to form a protostar.

Nuclear Fusion: When the temperature and pressure in the core became high enough, hydrogen nuclei began fusing together to form helium nuclei, releasing massive amounts of energy.

Stable Equilibrium (Main Sequence): The inward force of gravitational collapse was balanced by the outward thermal pressure caused by the energy released from nuclear fusion reactions, creating a stable star.

Explain the red-shift from galaxies which are receding

Stretched Wavelengths: Light emitted from distant galaxies travels toward us across expanding space. As the galaxy moves away (recedes), the light waves it emits get stretched out to longer wavelengths.

Shift to the Red End: On the visible spectrum, longer wavelengths correspond to the red end of the light spectrum. Therefore, the observed light appears shifted toward red ("red-shift").

Recession Indicator: The greater the observed red-shift of a galaxy's light, the faster that galaxy is moving away from us.

Explain that the relationship between the distance of each galaxy and its speed is evidence of an expanding universe model

Observations show that more distant galaxies exhibit greater red-shift, meaning they are moving away from us at higher speeds. This proportional relationship between distance and recession speed proves that space itself is uniformly expanding, rather than galaxies simply traveling through fixed space.

Explain how the evidence of an expanding universe leads to the Big Bang model

Rewinding Time: If the universe is currently expanding and galaxies are moving apart, rewinding time means everything in the universe must have been closer together in the past.

A Single Dense Point: Going back roughly 13.8 billion years suggests that all matter and energy in the universe originated from a single, extremely hot, and infinitely dense point (a singularity).

Initial Expansion: The 'Big Bang' theory proposes that the universe began from this point with a rapid expansion, and it has been expanding and cooling ever since.

What is the difference between a correlation and a cause-effect link?

: A correlation shows two factors change together, but a cause-effect link requires a plausible mechanism proving one factor directly produces/affects the outcome.

What is peer review and why is it important in science?

Scientific findings are evaluated and checked by other experts in the same field before publication to detect errors, prevent bias, and ensure results are reproducible.

How do scientific theories develop when new evidence contradicts them?

Theories are modified or replaced only when sufficient new evidence emerges and a better explanatory model becomes available.

What are the primary types of scientific models?

Representational/Spatial (analogies/visuals) Descriptive (explaining phenomena), Mathematical/Computational (using equations/data to predict behavior).

What are the advantages and limitations of using models in science?

Advantages: Allows safe, quick investigation without practical or ethical limits. Limitation: A model is only as accurate as its assumptions and may simplify the real world.

State the forms in which energy is released during a fusion reaction

Energy in the form of Gamma Rays

What is a nebula

A spinning cloud of dust and gas

What is a Protostar

A star in which nuclear fusion is just beginning to start

What is a main sequence star

A star which is undergoing nuclear fusion at a steady rate

What is a Red Giant

An old star which is beginning to run out of nuclear fuel

The order in which a star is produced

A spinning cloud of dust and gas

The forge of gravity causes particles to get closer together and speed up

Work done by gravity leads to increase in KE of particles

KE is large enough to overcome electrostatic repulsion between nuclei- nuclear fusion starts

Radiation pressure from nuclear fusion balances inward force of gravity

Explain how the solar system was formed from a spinning ball of dust and gas

Nebula Collapse: Gravity pulls a spinning cloud of dust and gas together, forcing particles closer and causing them to speed up.

Disk Formation & Work Done: Most mass collects at the center to form the Sun while the surrounding cloud flattens into a spinning disk; work done by gravity increases the kinetic energy (KE) of the particles.

Ignition of Nuclear Fusion: High KE allows hydrogen nuclei to overcome electrostatic repulsion so that, due to the high temperature, nuclear fusion begins.

Protoplanet Accretion: Dust and ice particles clump together over time to form protoplanets, which grow steadily larger by gathering more mass.

Inner Rocky Planets: High temperatures near the Sun allow only heavy, rocky materials to condense, forming the rocky inner planets.

Outer Gas Giants: Lighter, gaseous materials remain stable further away from the Sun where it is cooler, forming the giant gas planets that orbit the Sun in the same plane.

Explain why the centripetal force required increases with the increase in the speed of the object (at a constant radius)

At a higher speed, an object travels a greater distance along the curved path in a given time, requiring a larger change in its direction per second. Because acceleration is the rate of change of velocity, this sharper change in direction means the centripetal acceleration increases. According to Newton's Second Law ($F = ma$), a greater acceleration requires a larger net centripetal force to keep the object moving in that same radius.

Explain why the centripetal force required decreases with a larger radius of the circle (at a constant speed)

At a larger radius, the path is less curved, meaning the object's direction of motion changes more gradually over time. This smaller change in direction per second results in a lower rate of acceleration toward the center. Since force equals mass times acceleration ($F = ma$), a smaller acceleration requires a smaller centripetal force to hold the object in orbit.

State and Explain what will happen to the speed and the orbital radius of the ISS over time.

Effect on Orbital Radius: The orbital radius decreases over time (orbital decay).

Cause of Decay: Air resistance causes drag, which does work against the ISS and reduces its total mechanical energy.

Conversion of Energy: As the orbital radius drops, gravitational potential energy (GPE) is converted into kinetic energy (KE).

Effect on Orbital Speed: The orbital speed increases because the gravitational force is stronger at a smaller radius, requiring a higher speed to maintain a stable orbit at the lower altitude.

Describe how orbital speed varies with average distance from the sun

the orbital speed decreases significantly as the distance increases at a decreasing rate

Use ideas about energy transfer to explain why the comet is fastest when it is closest to the Sun.

The GPE of the comet gets transferred to the KE of the comet. As the comet cmes closer to the sun the GPE decreases so the KE increases It speed is greatest when it is closest to the sun

What is Density

Mass per unit volume of material

What is the formula for density?

What are the unitys for density

g/cm3

kg/m3

How to measure the density of an irregular solid

Measure the mass using a mass balance

Fill a displacement can to the spout.

Immerse the object fully and measure the volume of water displaced

calculate density using formula

How to measure the density of a regular solid

Measure the mass using a mass balance

Measure dimensions using a metre rule to calculate the volume (cuboid= l*w*h, Prism=l* s-c area *h)

Then divide the mass by the volume

How to measure the density of a liquid

Measure Empty Mass: Place an empty measuring cylinder on a mass balance and record its mass.

Record Total Mass & Volume: Pour a known volume of liquid into the cylinder and record the new combined mass.

Calculate Mass of Liquid: Subtract the mass of the empty cylinder from the total mass.

Calculate Density: Divide the mass of the liquid by its volume using formula

What is internal energy

The energy stored in a material, often associated with temperature rise. A combination of KE of the particles in the system and energy stored in bonds between particles.

What is Specific Heat Capacity (SHC)

The increase in internal energy required to raise the temp of 1kg of a substance by 1 degree C

What is specific latent Heat

THe increase in internal energy required to change the state of 1kg of a solid to liquid (SLH of fusion)

OR of 1kg of a liquid to a gas (SLH of vaporisation)

NO CHANGE IN TEMPERATURE

What is the difference between SLH of fusion and vaporisation

Fusion- Solid- Liquid

Vaporisation-Liquid-Gas

What is the formula and units for Specific Heat Capacity (SHC) and units

Specific latent heat formula and units

What is happening between A and B on the changing state graph

Electrical heater is doing work, raising the

internal energy of the solid at a

uniform rate. The temperature of the solid is rising at a uniform rate

What is happening between B and C on the changing state graph

Electrical heater is still doing work raising

the internal energy of the ice at a uniform rate

BUT the temperature is not rising. The hidden

(latent) energy is heating the ice, changing its

state from solid to liquid.

The change in density from solid to liquid is

small

Energy being used to break intermolecular forces not increase temp

MELTING POINT

What is happening at C on the chaning state graph (end of first plateu)

All the ice has melted and the temperature

of the liquid water rises at a uniform rate again.

The graph is about half as steep as it was when

heating ice; the specific heat capacity of water is

nearly twice as large as the s.h.c. of ice. The

same amount of energy gives half the

temperature rise

What is happening at D of the changing state graph (second plateau)

The water starts to boil. The energy

transferred by the heater is changing the state of

the water from liquid to gas.

The change in density from liquid to gas is very

great; a small volume of liquid produces a large

volume of gas

What a moving object hits an obstacle what two energy stores are equal

KE before the collision= internal energy

ASSUMING 100% EFFICIENT ENERGY TRANSFER

When an object slows down which transfer pathway and which store are equal

Work done by decelerating force= internal energy

ASSUMING 100% EFFICIENT ENERGY TRANSFER

Whan water is brought to a boil in a kettle which transfer pathway and which store are equal

Electrical work= internal energy

ASSUMING 100% EFFICIENT ENERGY TRANSFER

Explain why water is preferred over oil in central heating systems

Water has a higher SHC than oil, As water coold this means it gives out more energy per degree C of temp change than oil

Explain why water is preferred over air as a coolant

Water has a higher SHC than air.

Therefore it gains more energy from the hot object it is cooling per degree C of temp rise

Describe a Practical to investigate the SHC of a solid (metal)

Explain how you would increase the accuracy in a SHC experiment

Add insulation

Read the Thermometer at eye level to eliminate parallax

Describe an experiment to investigate the SHC of a liquid

How would you increase the accuracy in a SHC experiment of a liquid

Insulate & Cover: Use an insulated container (like a polystyrene cup) and place a lid on top to reduce heat loss via convection and evaporation.

Stir Continuously: Stir the liquid gently so thermal energy distributes evenly throughout the water before taking temperature readings.

Submerge Fully: Ensure the heater element is completely under the surface so energy isn't lost directly to the air above.

Describe an experiment to investigate the SLH of fusion

What is meant by the properties of solids liquids gasses

Something we can observe or measure

Density

Fluidity

Compressibility

Describe the properties of Solids, Liquids, Gases

Solid:Dense, incompressible, fixed shape

Liquid:Dense, Incompressible, Fluid, fixed volume but can change shape

Gas:Low density, compressible,fluid,no fixed shape or volume

Describe the separation of particles in of Solids, Liquids, Gases

Solids: Particles touch each other

Liquids: Particles touch each other

Gases: Very large separations

Describe the motion of particles in Solids, Liquids, Gases

Solids: Vibrate about a fixed position

Liquids: Slide past each other

Gases: Free to move in random directions, collisions between particles

Describe the arrangement of particles of Solids, Liquids, Gases

Solids:Regular Lattice

Liquids:Irregular

Gases:Irregular

Why is energy required to change state at a constant temperature during melting

To weaken bonds/forces of attraction, slight increase in particle separation, so energy must be supplied

Why is energy required to change state at a constant temperature during boiling

To completely break bonds, fully overcome forces of attraction

Large increase in separation

Which needs more energy supplied Melting or Boiling

Boiling

What is tension

The force in a cable or string when it is stretched tight.

100N of tension, there is 100N force pulling at each end of the cable

What is extension

The difference between the original length of a stretched material and its stretched length

What is Compression

The balanced inwards forces on an object that acts to reduce its size along the line of the force

What is an elastic object

A material that returns back to its original dimensions after any deforming forces are removed

What is a plastic object

When the material does NOT return to its original dimensions when the deforming forces are removed

What is elastic deformation

In stretching, it s the greatest extension that can be obtained while the material extends elastically

How many forces are needed to change the shape of an object

More than one, eg compressing a lime two forces

Describe an experiment to measure the effect of force on a spring

What is a risk during the experiment of measurign the effect of a force on a spring

The spring breaking- wear eye protection

When does Hooke's law not apply

If a material is stretched past its elastic limit, then it shows plastic deformation and the forse is no longer directly propn to the extension.

How to model a polymer

Very long molecules made of thousands of particles joined together in chains

What is hooke's law

Extension is directly propn to the force applied until the it reaches its elastic limit

Force v extension graph for Rubber bands

Know how to calculate area under a curve in a graph by counting squares

Yes

What is the formula for pressure and units

What is the formula for pressure variation with depth of fluid.

What does this assume

Constant density

What is upthrust (buoyancy) and what causes it?

Definition: The upward force acting on an object submerged in a fluid.

Cause: Pressure increases with depth, so fluid pressure on the bottom of an object is greater than on the top.

Result: This pressure difference creates a net resultant force upwards.

How do weight, upthrust, and density determine whether an object floats or sinks?

Sinks: Weight > Upthrust (resultant force downwards).

Floats: Weight = Upthrust (forces are balanced).

Density Rule: An object floats if its density is less than the fluid's density.

For a fixed mass of gas what is the volume of the gave propn or inversely propn to the pressure, and what does this assume

Vol inversely propn to the pressure provided the temp doesn't change

What is Boyle's Law?

P1V1=P2V2

What is Archimedes Principle

The Buoyancy force on a submerged object is equal to the weight of fluid displaced by the object

Explain why a seal pack of crisps when brought up a mountain has expanded

Air inside the packet is at 1 atmosphere of pressure (101.3kPa)

As we climb, outside atmospheric pressure decreases because there is a lower weight of air pushing down above you

There is a net force outwards on the packet causing it to expand

Why does pressure decrease at a higher altitude

Less Air Above You: Air pressure is caused by the weight of the atmosphere pressing down. At high altitudes, there is a shorter column of air above you, so there is less mass of air pressing down.

Lower Density: Air particles spread out and become less dense at higher altitudes, meaning fewer gas molecules per unit volume.

Fewer Collisions: With fewer air molecules present, there are fewer collisions against surfaces per second, resulting in a lower force per unit area (lower pressure).

How do Gas particles exert pressure

Particles collide with the wall and rebound

Change of momentum as the wall exerts a force on it.

N3L particles must also exert a force on the wall.

The result of these many collisions per second per unit area means a pressure is exerted on the container

What happens to pressure when volume reduces at a constant temperature

Particels have the same average speed

So each collision has the same change in momentum and each particle exerts the same force on the container.

There are more particles per unit volume of gas so there are more collisions per second per unit area, so the pressure increases

What happens to pressure when temperature increases at a constant volume

Particles have a greater average speed

Change in momentum from each collision increases

Therefore the force of each collision increases

More frequent collisions

More collisions per second per unit area

Pressure increases

Newtons 3rd Law

When object A exerts a force on object B, B exerts a force of equal magnitude and opposite direction back on A