P1- Conservation and dissipation of Energy Flashcards
What is a system?
What is a closed system?
1) A system is an object or group of objects.
2) A closed system is a system in which no energy transfers take place out of or into the energy stores of the system.
How can Energy be stored?
How can Energy be transferred?
1) Energy can be stored in a variety of different energy stores.
2) Energy can be transferred by heating, by waves, by an electric current, or by a force when it moves an object.
What happens when an object falls and gains speed?
1) When an object falls and gains speed, its store of gravitational potential energy decreases and its kinetic energy store increases.
What happens when a falling object hits the floor without bouncing back?
1) When a falling object hits the ground without bouncing back, its kinetic energy store decreases. 2) Some or all of its energy is transferred to the surroundings, the thermal energy store of the surroundings increases and energy is also transferred by sound waves.
What does the conservation of energy state?
1) The conservation of energy states that energy cannot be created or destroyed
Can energy be transferred between energy stores within a closed system?
1) Energy can be transferred between energy stores within closed systems. The total energy of the system is always the same, before and after any such transfers.
What is work done?
How do you calculate work done?
Where is work done to overcome friction transferred to?
1) Work is done on an object when a force makes the object move.
2) Work Done(W) = Force(F) x Distance(S)
3) Work Done to overcome friction is transferred as energy to the thermal energy stores of the objects that rub together and to the surroundings.
When would the gravitational potential energy tore of an object increase or decrease?
1) The gravitational potential energy store of an object increases when it moves up. It decreases when it moves down
Why does the gravitational potential energy of an object increase when lifted?
1) When lifted, work is done on the object to overcome the gravitational force.
What is the gravitational field strength like at the surface of moon compared to the earth?
1) The gravitational field strength at the surface of the moon is less than on earth.
Give the equation for working out:
The change in an objects gravitational potential energy store.
The change of gravitational potential energy store.
1) Change in an objects gravitational potential energy store= weight(N) x change of height(M)
2) Change of gravitational potential energy store= Mass(Kg)x gravitational field strength(N/Kg) x change of height(M)
What does the energy in a kinetic energy store of a moving object depend on?
1) The energy in the kinetic energy store of a moving object depends on its mass and speed.
Give the equation for:
Kinetic Energy
Elastic Potential Energy
G.P.E
1) Kinetic Energy: Ek = 1/2 x M(ass) x V^2 (speed)^2
2) Elastic Potential Energy: Ee = 1/2 x K (Spring constant) x E^2 (Extension)
3) G.P.E: g.p.e = m(ass) x g(raviational field strength) x h(eight)
Explain what useful energy is and what wasted energy is.
Where will wasted energy eventually be transferred?
1) Useful energy is energy in the place we want and need.
2) Wasted energy is energy that is not useful and energy that is transferred by an undesired pathway
3) Wasted energy will eventually be transferred to the surroundings which will become warmer.
What happens to energy as it spreads out (dissipates)?
1) As energy dissipates it gets less and less useful.
