topic 3 Flashcards
which of these is a non renewable?
A) geothermal
B) natural gas
C) tidal
D) solar
B) natural gas
explain why renewable sources provide an increasing fraction of the electricity supply for many countries
increased use of renewables because they dont emit greenhouse gases contributing to climate change
experiment with projecting small trolley up sloping track
state measurements student needs to make to complete investigation
first measure the mass of the trolley as well as the vertical heights and repeat for a range of masses. repeat firing with the same mass
describe an energy transfer that occurs when the student lifts the toy car form the bench and places the toy at the top of the slope
chemical transfers to GPE
state other measurements needed to determine loss in potential energy and gain in kinetic energy as toy car is rolling down the slope
vertical height and mass of the toy car
calculate energy transferred to surroundings when toy car rolls down the slope
GPE - KE at bottom
describe how the student could find by experiment the speed of the toy car at the bottom of the slope
measurement of distance and time and use speed = distance / time. repeat experiment and take an average
calculate the minimum height that 7.0kg of water must fall to gain 1300J of kinetic energy
PE = m x g x h
h = 1300 / 7 x 10
= 19m
as water moves the turbine at the bottom of the dam the kinetic energy of 8.0kg of moving water is 1100J calculate the speed of the moving water as it enters the turbine
ke = 1/2 x m x v
v = square root of 12 x 1100 / 8
v = 17
kettle - efficiency of 91% in supplying energy to the water
thermal energy of water increases by 3.3 x 10^5J in 200s
calculate the total amount of energy supplied to kettle in 200s, use:
efficiency = (useful energy transferred by the device) / (total energy supplied to the device)
energy supplied = useful energy / efficiency
= 3.3x10^5 / 91
= 3.6 x 10^3
