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
