Physics Final Ka Year 10 Flashcards
What is the equation for density?
Density = mass ÷ volume
What do you find the volume of a regular shape?
Volume = L x W x H
What is the density of water?
1g/cm³
How do you find the density of an irregular shape?
Volume: Fill measuring cylinder with 100ml of water. Place object in water and measure the difference.
Mass: weigh the object.
Density: mass ÷ volume
Units - g/cm³
When measuring the density of an irregular object in water what does it mean when the object floats or sinks
If it floats it is less dense than water (below 1g/cm³).
If it sinks it is denser than water (above 1g/cm³).
What is the word for a solid turning into a gas?
Sublimation
Explain the particles in a solid, liquid and gas
Solid: there are strong forces holding the particles in a fixed pattern.
Liquid: some of the particles break and are less organised but they are still close together
Gas: the remaining bonds are all broken and the particles move randomly
Which state of matter can be compressed most easily?
Gas
Which state of matter do the particles have the most energy?
Gas
Do particles in a solid stay still?
No they vibrate
Explain shape and volume in the three states of matter
Solid: has a fixed shape and volume
Liquid: no fixed shape, fixed volume
Gas: does not have fixed shape or volume
Explain the internal energy
The internal energy is made up from the kinetic energy of the moving particles and the potential energy as bonds are stretched. Heating a solid increases it’s internal energy because the particles move further and faster. When the material changes the state we don’t lose any particles and so the mass stays the same.
Which particles leave the quickest when evaporation takes place
The most energetic ones
Why do you feel cold when you are wet?
Your skin is using energy to evaporate the water
What is an example of condensation?
When water molecules in the air from a liquid on a window
If the units of mass are kg, and the volume m³, what are the units of density?
Kg/m³
If the units of mass are g, and the volume m³, what are the units of density?
g/cm³
What is the latent heat of fusion?
The energy needed to change a solid into a liquid
What is the equation for energy (involving latent heat)
Energy = mass x specific latent heat of fusion
E= M x Lf
What is the units for latent heat of fusion?
J/kg
What is latent heat of vaporisation?
The energy needed to change a liquid into a gas
What is the equation for energy (including latent heat of vaporisation)
Energy = mass x latent heat of vaporisation
E= M x Lv
What are the units for energy?
J
The latent heat of fusion of a substance is 500J/kg. How much energy will be needed to melt 200g of it.
Energy = M x Lf
= 500 J/kg x 0.2kg = 100J
As a gas cools what happens to the particles?
They slow down and lose kinetic energy
What is conduction?
When a substance is heated, its particles gain energy and vibrate. This passes the thermal energy through the substance by conduction, from the hot end to the cold end.
What is radiation?
All objects transfer thermal energy by infrared radiation. The hotter an object is, the more infrared radiation it gives off. Radiation doesn’t need moving particles
How does conduction work?
In metals there are lots of free electrons that move around at random inside and hold the positive ions together.
Explain what happens when a metal rod is heated
At one end the free electrons at the hot end gain kinetic energy and move faster. They diffuse and collide with the cold end and heat up the whole rod
What do hot objects emit?
Infra-red (I.R)
What colours emits heat the best/worst?
Black -best
Silver - worst
What affects heat loss?
- room temp
- material of container
- colour of container
- insulation
- time
- volume of substance
- surface area
What does a larger surface area and a smaller volume do?
Loses heat quicker
What is the specific heat capacity of a material?
The amount of energy needed to change the temperature of one kilogram of material by 1°c
What is the equation for energy? (Involving SPC)
Energy = mass x SHC x temperature change
What are the units of specific heat capacity?
J/kg°c
What are the different types of energy?
Heat, kinetic, light, chemical, gravitational potential, elastic potential, sound, electricity and nuclear energy
What does a TV do with energy?
Turn electrical energy into light, sound and heat energy
Where is the energy stored in a torch?
In the battery
What does the law of conservation of energy state?
Energy cannot be created or destroyed. We can use machines to change energy from one type to another
What is work done equal to?
The energy transferred
What is the equation for work done?
Work done (J) = force (N) x distance moved (M)
What is the equation for power?
Power = work done ÷ time
Or
Energy ÷ time
What are the units of power?
J/s or W
What happens to GPE when you lift something higher or if you have a larger mass to raise?
It increases
What is the equation for change in gravitational potential energy?
Change in GPE = mass x gravitational field strength x change in height
What are the units for GPE?
J
What are the units of gravitational field strength?
N/kg
What is the equation for kinetic energy?
Kinetic energy = 1/2 x mass x speed²
When something in an equation is squared and you are trying to find what it is what must you do before you give an answer?
Square root it
What is the equation for efficiency?
Efficiency = (useful output energy ÷ total energy supplied) x 100%
What makes a machine efficient?
Producing very little waste
What are some renewable resources?
Wind, solar, waves, bio-mass, wood
What are some non renewable resources?
Coal, oil, gas, nuclear
What is the problem with non renewable resources?
When burnt they give out CO₂ which is a wast product that causes global warming.
Nuclear can cause leak of radiation and give off radioactive waste which causes deficiencies and cancer
What is a current?
A flow of charged particles. The rate of flow of charge
What is a series circuit?
A circuit with one path for a current to flow around
What is the conclusion of a parallel circuit?
The sum of the currents in the branches equal the current entering or leaving the cell (battery).
What is the equation for charge?
Charge = current x time
Q = I x T
What is the unit for charge?
Coulomb, C
What is the unit for current?
Ampere, A
What is the equation for energy transferred?
Energy transferred = potential difference x charge
What is the unit for potential difference?
Volt, V
What puts energy into a circuit?
A battery of power supply
What does the p.d measure?
The amount of energy given to each coulomb of charge
When components are connected in parallel, what is the total current?
The sum of the currents in each loop
What happens to the current when resistance is added?
Less current flows
What does using a larger potential difference do to a lamp?
Increases the current and lamp brightness
What causes resistance?
Collisions between the moving electrons and the vibrating ions in the wire
What is the equations for resistance?
Resistance = potential difference ÷ current
What is the unit for resistance?
Ω
In a series circuit what current passes through each component?
The same current
What is the total potential difference of the voltage supply in a series circuit?
It is shared between the components
The current through a resistor (at constant temp) is _____ to the voltage across the resistor
Proportional
What are semi conductors?
Found on the boundary between metals and non-metals
What do semiconductors do when they don’t have energy and when they do?
The behave as insulators with no free electrons.
Then when we put energy in they release electrons, a current can flow and the resistance reduces
What is a diode?
A diode is made of two pieces of semi conductor, treated so that electrons will only flow directly across the boundary. They allow current to flow forward and not backwards
The sum of the P.d of the components in a series circuit equals ___ ____ __
The supply p.d
The p.d across each component in a parallel circuit ______________
Equals the battery p.d
What colour is the earth wire and where is it?
Striped and at the top (middle)
What colour is the live wire and where is it?
Brown and on the right
What colour is the neutral wire and where is it?
Blue and on the left
What are the pins made from in a plug and why?
Brass because it is a good conductor and it strong so it doesn’t bend or rust
What is the plug body made from plastic?
Because it’s a good insulator
Why does the fuse melt when the current is too large?
So the circuit doesn’t break
What does the cable grip in a plug do?
Stop the wire being pulled out of place
What happens to the resistance of a filament lamp as the temp increases?
It increases
Why does a diode have a high resistance in the reverse direction?
To help it only flow in the forward direction
If a current is 10V, what fuse would you use?
13A fuse
What does the earth wire do?
The earth wire provides a low resistance path for the current to flow from the live wire.
What would happen if an earth wire is missing?
You would get an electric shock if you touched whatever it was in
What is the name of a current that only goes in one direction?
A direct current
What is an alternating current?
A current that repeatedly reverses its direction. It flows one way then the other.
What is an alternating currents frequency?
The number of cycles it passes through each second
What is a typical power stations alternating potential difference of electricity?
2500V
What is a step up transformer?
They are used at power stations to transfer electricity to the national grid, they increase the voltage
What are step down transformers?
They transfer electricity from the national grid to consumers. They reduce the voltage
What happens when you make the grid potential difference very large?
Much less current is needed to transfer the same amount of power so the power loss due to the cables is reduced. This means it is an efficient way to transfer electricity
What is an oscilloscope used for?
To show how an alternating potential difference changes with time
What is the national grid made up of?
A system of cables and transformers
What is the equation for power loss in a cable?
I²R
What is the equation for P.d (including charge)
P.d = energy ÷ charge
What are non contact forces?
Forces that have a region around them called a field where they affect objects
What is a scalar?
A quantity that only have size
What is a vector?
A vector has a size and direction
What is Newton’s first law?
If there are no forces acting on an object or if the resultant is zero: a stationary object will remain at rest and a moving object will continue at the same speed and in the same direction
What is the resultant of a plant pot which has a weight of 5N and a support force of 5N?
0
What are the forces acting on a submarine sailing under water?
Support going up
Weight going down
Engine thrust going forwards
Drag force going backwards
When a plane lands, what is the direction of the resultant?
Backwards
What is the resultant force of a plane that has stopped?
0
What is newtons 3rd law?
When 2 objects interact they exert equal and opposite forces on each other
What is the resultant force?
The single force that can replace all of the forces acting on an object and have the same effect
What is the equation for weight?
Weight = mass x grav. Field strength (N/Kg)
What is inertia?
An object wanting to stay where it is or to continue moving in the same way
What is the equation for inertial mass?
Inertial mass = force ÷ acceleration
What is terminal velocity?
The velocity reached by an object when the drag force on it is equal and opposite to the force making it move
An object is released in a fluid. Describe the resultant force on it initially
Weight - frictional force
What is the equation for stopping distance?
Stopping distance = thinking distance + braking distance
What is the equation for thinking distance?
Thinking distance = speed x reaction time
What is the equation for kinetic energy?
Kinetic energy = 1/2 x mass x speed²
KE= 1/2mv²
What do the brakes convert KE into?
Thermal energy
What does a flat bit mean on a graph that is in stages?
Represents the changing of state
What equation do you use for the slopes on the graph? (States of matter)
specific heat capacity
What equation do you use for the flat parts on the graph? (States of matter)
Latent heat
What are the rules of energy
You cannot create/make or destroy it
What are some problems of renewable resources?
You need a lot of them.
Thinly spread
Visual and noise pollution
Unreliable
Draw the basic circuit symbols on sheet
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