energy changes in a system Flashcards
(14 cards)
what is the equation for kinetic energy
1/2 x mass x velocity2
energy-J
mass-kg
velocity- m/s
what is the equation for elastic potential energy
1/2 x spring constant x extension2
energy-J
spring constant-n/m
extension-m
what is the equation for gravitational potential energy
mass x gravitational field strength x height
mass- kg
gravitational field strength- N/kg
height-m
define the specific heat capacity of a substance
the amount of energy needed to raise the temperature of 1kilogram of a substance by 1 degree celcius
state the units of specific heat capacity
J , C/kg
.joules/degree celsius/kilogram
what is the defonition of power
the rate at which energy is transferred, or work is done
state 2 equations for power
power=energy transferred/ time
power= work done/time
energy-j
work done-J
time- s
what is the unit of power
Watt W
describe the energy changes involved when a ball is thrown upwards and then returns to its starting position. ignore air resistance
. upwards- kinetic energy is converted to gravitationsl potential energy
.peak- maximum gravitational potential energy, 0 kinetic energy
.downwards GPE is converted to kinetic energy
describe the energy transfers for a bungee jumper
. when falling the gpe is converted to to ke of jumper
.as the cord tightens, ke is converted and stored as elastic potential energy
. at lowest point, the jumpers intial GPE equals the EPE stored in the cord
explain why a bungee jumper slows down once the cord begins to stretch
.kinetic energy decreases since its converted to elastic potential energy
.since ke is proportional to velocity2 , as KE increases so does velocity.
give examples of chemical energy stores
.food
.fuel e.g-wood,coal,petrol
.batteries
state 4 different stores of energy
. kinetic energy
.gravitational potential energy
.elastic potential energy
.chemical energy
