p7.1

Question 1

what voltage and frequency are mains at?

Answer 1

230V

and 50Hz

Question 2

what are the 4 ways energy can be transferred

Answer 2

mechanically
electrically
elastically
heating by particles
heating by radiation

Question 3

equation to calculate how energy transferred mechanically?

Answer 3

work done = force x distance

Question 4

equation to calculate how energy is transferred electrically?

Answer 4

energy transferred = power x time

Question 5

equation for kinetic energy?

Answer 5

1/2 mv^2

Question 6

what is another way of writing out 1N?

Answer 6

1 kg m/s^2

Question 7

what is another way of writing out 1J?

Answer 7

1 Nm

Question 8

in a car accelerating how does the energy store change?

Answer 8

more chemical store vs kinetic store

THEN

more kinetic store vs chemical store

Question 9

what is the transfer between a braking car?

Answer 9

initially -
more in kinetic store than thermal store

final -
more in thermal store than kinetic store

WORK DONE BY BRAKES SLOW CAR DOWN kinetic -> thermal stores of break pad

Question 10

equation to calculate energy/work in a spring

Answer 10

e = 1/2 kx^2

energy = 1/2 x spring constant x compression^2

Question 11

how would energy stores change of a spring being compressed (due to a gymnast)?

Answer 11

initial - elastic low
kinetic - nothing
gravitational high

middle - elastic mid
kinetic high
gravitational mid

final - elastic high
kinetic - nothing
gravitational = little

Question 12

equation to calculate change in energy in gravitational store

Answer 12

e = mgh

energy = mass x gravitational field strength x change in height