Everything Mocks Flashcards
When energy is ________ to an object, the energy is _________ in one of the objects energy stores
Transferred…stored
The energy stores you need to know are
Thermal energy stores Kinetic energy stores Gravitational potential energy stores Elastic potential energy stores Chemical energy stores Magnetic energy stores Electrostatic energy stores Nuclear energy stores
Energy is transferred _______________ (by force doing work), ____________ electricity (work done by moving charges), by ___________ or ___________
Mechanically…electrically…heating…radiation
What is a system?
A single object or a group of objects
When a system changes, energy is ____________
Transferred
What are closed systems
Systems where neither matter nor energy can enter or leave
The net change in the total energy of a closed system is always zero
Work done
Another way of saying energy transferred
Work can be done when current flows or by a force moving an object.
Throwing a ball upwards?
Energy transfer from the chemical energy store of the person’s arm to the kinetic energy store of the ball and arm
A ball dropped from height?
Causes energy to be transferred from the ball’s gravitational energy store to it’s kinetic energy store
Friction between a car and a stationary object?
Causes an energy transfer from the wheels kinetic energy stores to the thermal energy store of the surroundings
Collision between a car and a stationary object?
Causes energy to be transferred from the car’s kinetic energy store to other energy stores
Solids arrangement and energy of particles
Strong forces of attraction hold the particles close together in a fixed, regular arrangement.
The particles don’t have much energy so they can only vibrate about their fixed positions
Liquids arrangement and energy
Weaker forces of attraction between particles.
Particles are close together, but move past each other and form irregular arrangements.
They have more energy than the particles in a solid
Move in random directions at slow speeds
Gas arrangement and energy
Almost no forces of attraction between particles
Particles have more energy than in liquids and solids
Free to move
Constantly moving with random directions and speeds
Colliding gas particles
As they move, they collide with each other and whatever is in the way (like the sides of a container) and exert a force called pressure.
In a sealed container, the outward gas pressure is the total force exerted by all particles in the gas.
Increasing temperature of a gas
If temperature is increased, you transfer energy into the kinetic energy stores of its particles.
The higher the temperature, the higher the average energy
The average speed of the particles increases
Increasing temperature increases pressure
What are isotopes
Are atoms with the same number of protons but a different number of neutrons
Alpha radiation
When an alpha particle is emitted from the nucleus.
Alpha particle
Two neutrons and two protons (like a helium nucleus)
Beta particles
A fast moving electron released by the nucleus.
No mass and a charge of -1
Gamma rays
Don’t change the charge of the nucleus
Waves of electromagnetic radiation released by the nucleus.
They penetrate far into materials
Absorbed by thick sheets of lead
Alpha decay
Decreases the charge and mass of a nucleus
e.g Uranium-238 alpha decayed is Thorium-234
238 234 4
U —> Th + He
92 90 2
Beta decay
Increases the charge of the nucleus
e.g Carbon-14 beta decayed is Nitrogen-14
14 14 0
U —> N + e
6 7 -1
Radioactivity
Energy made from the breakdown of atoms
What can radiation be measured with
A Geiger-Muller tube and counter, which records the count-rate (the number of radiation counts reaching it per second)
What is half life
Half-life is the time it takes for half of the unstable nuclei in a sample to decay or for the count rate to halve
Risks of radiation
Ionising radiation can enter living cells and ionise atoms within them. This can damage the cells or kill them
Exposure to radiation is called?
Irradiation
Gamma, Beta, Alpha - Which two are the most dangerous
Beta and gamma are most dangerous because they can penetrate the body.
Vector quantity
Have both magnitude and direction
Force, velocity, displacement, acceleration, momentum
Scalar quantity
Only magnitude
Speed, distance, mass, temperature, time
Examples of contact forces
Friction, air resistance, tension
Examples of non contact forces
Magnetic force, gravitational force, electrostatic force
Equation for weight
Mass (kg) x gravitational field strength (N/kg)
Gravitational field strength on earth
9.8 N/kg
Increasing the ___ increases the weight. They are directly __________
Mass…proportional
What is the resultant force
The overall force on a point or object
Work done equation
Force (N) x Distance (m)
Equation for force
Spring constant (N/m) x extension (m)
Extension is directly ______________ to ______
Proportional…force
Equilibrium means?
If an object is in equilibrium if the forces on it are balanced
Equation for elastic potential energy
1/2 x spring constant (N/m) x extension (m) ^2
Equation for velocity
Distance / time + direction
Equation for acceleration
Change in velocity (m/s) / time taken (s)
Drag increases as _____ increases
Speed
Newtons 1st Law of Motion
A force is needed to change motion
Newtons 2nd Force of Motion
Acceleration is directly proportional to resultant force
Newtons 3rd Law of Motion
When two objects interact, the forces they exert on each other are equal and opposite
Stopping distance equation
Thinking distance + Braking distance
Thinking distance is affected by
Your speed
Your reaction time
Braking distance is affected by
Your speed
The weather or road surface
The condition of your tyres
How good your brakes are
Momentum equation
Mass (kg) x velocity (m/s)
Transverse waves
Have sideways vibrations
The oscillations are perpendicular
Most waves are transverse e.g
Electromagnetic waves
Ripples and waves in water
A wave on a string
Longitudinal waves
Oscillations are parallel to the direction of the energy transfer
e.g sound waves in air
Equation for wave speed
Frequency (Hz) x wavelength (m)
Amplitude of a wave
Maximum displacement of a point on the wave from its undisturbed position
The wavelength of a wave
The distance between the same point on two adjacent waves
The frequency of a wave
The number of complete waves passing through a certain point per second
What to use to measure the speed of sound
An oscilloscope
What to use to measure the speed of water ripples
Ripple tank
When a wave hits a boundary, what three things can happen
The wave can be:
Absorbed, Transmitted, Reflected
What happens when the wave is absorbed
The wave transfers energy to the material’s energy stores
What happens if a wave is transmitted
The wave carries on travelling through a new material. Often leading to refraction
What happens if a wave is reflected
Where the incoming ray is sent back away from the material. This is how echoes are created
Refraction
Is waves changing directions at a boundary
