P1 ENERGY Flashcards
equation for kinetic energy?
1/2 x mass x (velocity)²
energy = j
mass = kg
velocity = m/s
equation for elastic potential energy?
1/2 x spring constant x (extension)²
energy = j
spring constant = n/m
extension = m
equation for gravity potential energy?
mgh
mass=kg
energy = j
gravitational field strength = n/kg
height = m
define specific heat capacity?
the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree celsius.
unit for specific heat capacity?
joules/degree celsius/kilogram
power meaning?
the rate at which energy is transferred
two equations of power?
power = energy transferred/time
power = work/done
power unit?
watt (w)
two motors lift the same mass through the same height. motor a does this is half time of motor b. which dissipates the most power?
motor a
the energy transferred is the same but time taken is less
describe the energy changes involved when a ball is thrown upwards and then returns to its starting position. ignore air resistance
upwards: ke is converted to gpe
peak : maximum gpe, zero ke
downwards : gpe is converted to ke
describe the energy transfer for a bungee jumper?
when falling the gpe is converted to ke of the jumper.
as the cord tightens, ke is converted and stored as elastic potential energy.
at lowest point , the jumper’s initial gpe equals the epe stored in the cloud.
explain why a bungee jumper slows down once the cord begins to stretch.
ke decreases since its converted to elastic potential energy.
since ke is proportional to velocity² , as ke decreases so does velocity
examples of chemical energy store?
food, fuel , batteries
4 different stores of energy?
kinetic energy
gravitational potential energy
elastic potential energy
chemical energy
kinetic energy?
energy stored in moving object.
elastic potential energy?
A force acting on an object may cause the shape of an object to change.
gravitational potential energy?
energy stored in an object due to its position above the earths surface.
equation for specific heat capacity?
change in thermal energy = mass x specific heat capacity x temp change