energy

Question 1

what are the eight energy stores?

Answer 1

chemical
electrostatic 
electrical
gravitational
kinetic 
magnetic 
nuclear
thermal

Question 2

work done =

Answer 2

force x distance ( mgh )

Question 3

power =

Answer 3

work done ( energy transferred ) / time

Question 4

kinetic energy =

Answer 4

1/2 x mass ( kg ) x v^2

Question 5

gravitational potential =

Answer 5

mgh mass in kg height in metres

Question 6

gravitational potential gain =

Answer 6

lose in kinetic

Question 7

what is power measured in?

Answer 7

watts

Question 8

efficiency = ( two ways )

Answer 8

useful output energy transfer / total input energy transfer OR useful power output/ total power input

Question 9

what is a system?

Answer 9

a group of objects

Question 10

what happens to the way energy is stored when a system changes?

Answer 10

it changes

Question 11

elastic potential energy =

Answer 11

0.5 × spring constant ( k ) × extension^2 ( m )

Question 12

change in thermal energy =

Answer 12

mass × specific heat capacity × temperature change

Question 13

what is specific heat capacity measured in?

Answer 13

joules/kg/degree celsius

Question 14

what is the specific heat capacity of a substance?

Answer 14

the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.

Question 15

an energy transfer of one joule / second = how many watts

Answer 15

1

Question 16

using examples illustrate the definition of power

Answer 16

when two motors both lift the same weight through the same height but one does it quicker

Question 17

generally what units of measurements are used in these formulas?

Answer 17

kg and metres

Question 18

give two reasons for taking repeat readings in an investigation

Answer 18

calculate a mean, spot anomalies, reduce the effect of random errors

Question 19

give a reason why doubling the diameter of the blades more than doubles the power output of a turbine.

Answer 19

• kinetic energy of wind more than doubles
• mass of air more than doubles
• area swept by the blades more than doubles