Topic 5: work/energy/power Flashcards
what are the 9 energy stores
heat, light, sound, kinetic, electric, chemical, gravitational potential, elastic potential, nuclear
what is the law of conservation of energy
energy can be transferred between stores but it cannot be created or destroyed.
how do you calculate efficiency using work
useful work out ÷ total work in
how do you calculate efficiency using power
useful power out ÷ total power in
define work done
the amount of energy transformed when a force acts in the direction of the movement.
what is the equation for work done
work done = force x distance
what is the lifting force required to lift an object
the weight of the object
define power
the amount of energy transformed per second
what are the units for power
W or J/s
what is the equation for power
power = work done ÷ time
what is an equation for power at constant velocity
power = force x velocity
what is the equation for gravitational potential energy
E = mgh
what is the equation for kinetic energy
E = ½mv²
what is an equation for velocity that can be derived from E = mgh = ½mv^2
v = √(2gh)
how do you connect gravitational potential energy, work done, and kinetic energy
GPE = work done + KE
mgh = Fs + ½mv²
