Energy

Question 1

what is energy?

Answer 1

the ability to do work

Question 2

what is the law of conservation of energy?

Answer 2

energy cannot be created or destroyed; only transferred

Question 3

what are the stores of energy?

Answer 3

kinetic
gravitational potential
thermal
elastic potential
chemical
nuclear
magnetic
electrostatic

Question 4

how can energy be transferred?

Answer 4

heating
mechanically (force causes something to move)
waves (light+sound)
electrically (only if electricity is used)

Question 5

what is a system?

Answer 5

an object or group of objects

Question 6

what happens in a closed system?

Answer 6

there’s no net (overall) change to the amount of energy in the system

Question 7

GPE equation

Answer 7

E=mgh

Question 8

KE equation

Answer 8

E=1/2mv²

Question 9

thermal energy equation

Answer 9

∆E=mc∆θ

Question 10

what is specific heat capacity; c?

Answer 10

the amount of energy needed to raise 1kg of a substance by 1 °C

Question 11

what is efficiency?

Answer 11

how good a device is at transferring energy usefully

Question 12

efficiency equation

Answer 12

efficiency=useful power or energy output/total power or energy input

Question 13

how do you improve efficiency?

Answer 13

insulation
lubrication

Question 14

what is power?

Answer 14

rate of energy transfer

Question 15

power equation

Answer 15

E=Pt

Question 16

what is renewable energy?

Answer 16

a source that can be replenished as it’s used

Question 17

examples of renewable energy sources

Answer 17

biofuel - plant matter waste
wind - wind current turbines
hydroelectric - dams of water= flood valley= gpe
geothermal - steam from hot ground
tidal - ke of tide (sea water)
solar - UV rays
waves - moving turbines connected to a generator

Question 18

pros and cons of biofuel

Answer 18

pros
- carbon neutral
- reliable
cons
- plants have to be destroyed

Question 19

pros and cons of wind

Answer 19

pros
- free
- safe for the environment
- no CO2 released
cons
- unreliable
- noise+sight pollution
- need LOTS to meet energy demand
- turbines=expensive
- kill birds

Question 20

pros and cons of hydroelectric

Answer 20

pros
- safe for environment
- no fuel cost
- energy on demand
- no CO2 released
cons
- destroys habitats
- methane released

Question 21

pros and cons of geothermal

Answer 21

pros
- no CO2 released
- no fuel cost
- good for envirionment
cons
- specific location needed

Question 22

pros and cons of tidal

Answer 22

pros
- no CO2 released
- no fuel cost
cons
- requires a coast

Question 23

pros and cons of solar

Answer 23

pros
- no CO2 released
- no fuel cost
cons
- panels= expensive
- unreliable= needs sunny weather
- max power?

Question 24

pros and cons of waves

Answer 24

pros
- safe for environment
- no CO2 released
- no fuel cost
cons
- unreliable

Question 25

what is non-renewable energy?

Answer 25

a source that cannot be replenished

Question 26

examples of non-renewable energy sources

Answer 26

fossil fuels (oil, coal, gas) - remains of dead marine life
nuclear - unstable nuclei in atoms eg. uranium or plutonium

Question 26

pros and cons of fossil fuels

Answer 26

pros
- give lots of energy=can meet high energy demand
- easy to use
- reliable
cons
- release CO2=enhance greenhouse effect

Question 26

pros and cons of nuclear

Answer 26

pros
- give out the highest amount of energy
- reliable
- no CO2 released
cons
- toxic waste=very dangerous= safety equipment needed=expensive
- how to store waste

Question 26

specific heat capacity practical

Answer 26

• measure mass of metal with a balance
• record start temp with a thermometer
• heat for 10 mins using a (emergent) heater
• record final temp with a thermometer
• measure energy used using a joulemeter
• use ∆E=mc∆θ to calculate shc

Question 26

how to reduce energy waste

Answer 26

Lubrication
o Oil in a motor
o Reduces friction
o So less energy is lost (as heat) through friction
- Thermal Insulation
o Double Glazing
o Less useful thermal energy lost