module 1 Flashcards
What are the energy stores?
thermal, kenetic, gravitational potentia, elastic potential,chemical, magnetic, electrostatic, neulear.
What is a system and what happens when they change
a single object, energy is transfered.
How does a system change?
it can be transferred into or away from the system between different objects in a system or between different objects in a system or between different types of energy stores
What are closed systems?
Systems where neither matter nor energy can enter or leave. The net change in teh total energy of a closed system is always zero.
In a boiling kettle what is the system? What energy store is is transfered into?
Water, water heating element and water are two-object system, thermal energy store.
How does energy transfer in kettle?
electrical to thermal energy store of heating element. Then by heating to water’s thermal energy store.
What does work done mean?
energy transfered
What can work done be compleated by?
electric flow, by a force moving on object
What is the first stage of someone throwing a ball in the air?
initial force exerted by person throws ball in air. Energy transferes from chemical energy store in arm to kinetic energy store of ball and arm
What is the second stage of a ball in air?
ball dropping accelerates from height by gravity, gravitational force does work. Energy transferes from ball’s gravitational potential energy store to its kenetic energy store.
How do energy and forces act on cars?
friction between car’s brakes and its wheel does work as it slows down. Energy transferes from wheel’s kinetic energy store to thermal store of its surroundings.
What happens in a car crash?
contact force between car and object does work, transfer from car kentic to other energy stores, some energy might be transfered by sound waves.
What are the 3 most common energy stores?
kenetic, gravitation potential, elastic potential
What does everything moving have? What happens with speed?
Kenetic energy store, accelerate- energy transfered to this store. Energy transfered away when it slows.
What does kinetic energy store depend on?
Mass and speed,Greater mass and faster the speed more energy in the kinetic energy store.
What is the formula for kinetic energy?
E(k)=1/2MVsquared m=mass kg v=speed m/s squared. E(k=(j)
What does lifting an objects gravitational field require?
work, causes transfer of energy to gravitational potential energy. Higher lifted more energy is transferred.
What does energy in gravitatial potential depend on?
mass, height, and strength
What is the equation for gravitational potential energy?
E(p)=mgh m=mass kg g= gravitational field strength (N/kg) h= height metres e(p)= (j)
What happens when an object falls?
gravitational potential energy store transfers to kenetic energy store. If no air resistance energy lost from gravitational potential energy =energy gained from kinetic energy store.
What happens with air resistence?
energy is transfered to other energy stores e.g.thermal energy stores of the object and surroundings
What is elastic potential energy caused by?
Squashing or streaching an object so long as limit of proportionality hasn’t been exceeded.
What is the equation for elastic potential energy?
E(e)=1/2ke squared E(e)=(j) k=spring constant (N/m) e= extension (m)
Materials need different amounts of heat energy to warm up than others. What do materials that gain lots of heat do?
Transfer lots of energy when they cool down. They ‘store a lot of energy’.