Unit 1 physics

Question 1

What is a system

Answer 1

an object or group of objects where the total amount of energy is fixed and due to the law of the conservation of mass, No energy can be made or destroyed, only transferred usefully.

Question 2

When we have an object with Chemical energy, what do we call it

Answer 2

A chemical energy store

Question 3

What happens to the energy store when the system changes

Answer 3

the energy store also changes. e.g. when a vehicle is slowing down, some of its kinetic energy is converted into thermal energy as a result of friction. E.g. a hairdryer is powered by electrical energy but when it is turned on, that energy is turned into sound and thermal energy.

Question 4

Formula for Kinetic energy

Answer 4

Ek= 1/2mv^2

Question 5

Formula for gravitational potential energy

Answer 5

Ep=mgh or Ep=Wh

Question 6

Formula for elastic potential energy not in a spring

Answer 6

Ee=1/2Fe

Question 7

Formula for elastic potential energy in a spring

Answer 7

Ee=1/2ke^2 (Hooke’s Law)

K=spring constant
e=extension

Question 8

what is specific heat capacity and what is the formula

Answer 8

The amount of energy required to increase the temperature of an object by 1’C.
E=m x c x change in t

c= specific heat capacity ( measured in J/Kg )
change in t= change in temperature

Question 9

What is efficiency

Answer 9

The percentage of input energy which can be converted into a useful out of the total amount of energy.

Question 10

Formula for efficiency

Answer 10

useful energy output/ total energy output

Question 11

How can we increase efficiency

Answer 11

-reducing the waste product by lubricating moving parts
-recycling the waste product by recycling thermal waste as energy to input back in

Question 12

How do we reduce energy wastage overall

Answer 12

-Lubrication of moving parts like in a motor as it reduces friction which means there is less waste thermal energy
-Thermal insulation such as double glazing windows so less thermal energy is lost

Question 13

What is thermal conductivity

Answer 13

How easily a material transfers heat energy to its surroundings. If a material has a high thermal conductivity, like metal, then it will lose heat energy very quickly

Question 14

What is power and give its formula. what is it measured in

Answer 14

The rate at which work is done.
Power= energy transferred/ time P=E/t or P=W/t
Power is measured in Watts

Question 15

Name some non renewable energy sources

Answer 15

-Crude oil
-Natural gas
-Coal
-Nuclear energy

Question 16

Name some renewable energy sources

Answer 16

-Biofuel
-Solar
-wind
-Tidal
-Geothermal
-Hydro-Electric

Question 17

What are the benefits of using renewable energy

Answer 17

-It can be replenished after use so it never runs out
-It doesn’t produce harmful by-products like CO2 or methane

Question 18

Why dont we use all renewable energy

Answer 18

-It is expensive
-Energy like solar or wind are weather dependent so many countries cant rely on it

Question 19

When would we use non renewable energy

Answer 19

Large scale energy supplies like powering the national grid due to the large amount of energy per Kg they provide

Question 20

Problems with non renewable energy

Answer 20

Burning fossil fuels causes damage to the environment and we only have a limited amount of them. extracting fossil fuels is also bad for the environment