P1 Flashcards
What are the ways energy can be transferred
-By heating
-by waves
-by an electric current
-by a force when it moves an object
What happens to an object when it falls and gains speed
Its store of gravitational potential energy decreases and kinetic energy store increases
What ways can energy be transferred
Heating, waves, electric current, by moving force
What energy is transferred in a falling object
Gravitational potential energy decreases, kinetic potential energy increases
What energy is transferred when an object hits the ground without bouncing
Kinetic energy store decreases, most energy transferred to surroundings and thermal energy store of surroundings increases
What is the conservation of energy principle
Energy cannot be created or destroyed
Where does conservation of energy apply
All energy changes
What is a closed system?
A place where no energy is transferred into or out of the system but can be transferred within it
What is work done
Energy transferred when an object is moved
Equation involving Force Distance and Work done
Work done = Force applied x distance moved from force
What force do you need to lift an object upwards
A force Equal to The weight (m x gf) of the object
What happens to gravitational potential energy stores when an object moves upwards
increases = work done by lifting force
What happens to gravitational potential energy stores when an object moves down
Decreases = to work done by gravity
Equation for change in gravitational energy store
Change in GES(J) =W(N) x Change in Height (M)
Equation for kinetic energy store
Kinetic energy (J) = 1/2x mass (Kg) x Speed(m/s^2]
Equation for emergy store of stretched elastic spring
Elastic potential energy (J) = 1/2x spring constant (N/m) x extension^2 (m^2)
What arebthe factors for the amount of kinetic enery in a kinetic energy store
Mass and speed
What is elastic potential energy?
The amount of energy stored in an elastic object when work is done on it
What is useful energy
Energy in the place we want it and the form we need it
What is wasted energy?
Energy that is not useful and transferred by an undesired pathway
What happens when energy dissipates (spreads out)
It gets less and less useful
What happens to wasted energy
Its eventually transferred to the surroundings which become warmer
Why might machines waste energy
-Friction between moving parts
-air resistance
-electrical resistance
-noise
How can you reduce the problem of friction wasting energy in machines
Lubricate the moving parts
