P1 - Conservation & dissipation of energy 1️⃣✅

Question 1

What are the 4 types of energy transfers?

Answer 1

Mechanical working
Heating
Waves e.g. light/ sound by radiation
Electricity

Question 2

What are all eight energy stores?

Answer 2

kinetic
magnetic
thermal
chemical
electrostatic
nuclear
elastic potential
gravitational potential

Question 3

What is the equation for kinetic energy?

Answer 3

Ek = 0.5 x m x v2

m = mass kg
v2 = velocity squared m/s

Question 4

What is the equation for elastic potential energy?

Answer 4

Ee = 0.5 x k x e2

k = spring constant N/m
e2 = extension squared m

Question 5

What is the equation for gravitational potential energy?

Answer 5

Eg = m x g x h

m = mass kg
g = gravity 9.8
h = height m

Question 6

What is the equation for weight?

Answer 6

W = m x g

m = mass kg
g = gravity 9.8

Question 7

What is the equation for power?

Answer 7

P = e/t

e = energy J
t = time s

Question 8

What is the unit for power?

Answer 8

Watts

Question 9

What is the equation for work done?

Answer 9

W = f x s

W = work done J
f = force N
s = distance m

Question 10

What is the equation for efficiency?

Answer 10

E = useful energy
——————-
total energy

Question 11

Energy cannot be ___________ or __________

Answer 11

Energy cannot be created or destroyed

Question 12

What is useful energy?

Answer 12

Useful energy is energy transferred to where it is wanted in a way that is wanted

Question 13

What does lubrication do?

Answer 13

Lubrication is a way of reducing unwanted energy transfer due to friction

Question 14

What does streamlining do?

Answer 14

Streamlining is a way of reducing unwanted energy transfer due to air resistance or drag

Question 15

Efficiency is a _________ of how much ________ is ___________ _________

Answer 15

Efficiency is a measure of how much energy is transferred usefully

Question 16

What is the unit of energy?

Answer 16

Joules

Question 17

How do you get from joules to kilojoules?

Answer 17

divide by 1000

Question 18

How do you get from kilojoules to joules?

Answer 18

multiply by 1000

Question 19

Describe the energy transfer when a moving car slows down

Answer 19

the energy is transferred via mechanical working from the cars kinetic energy store to the thermal store of its breaks. Some energy is dissipated into the thermal store of the surroundings

Question 20

What does dissipated mean?

Answer 20

When energy is dissipated, essentially it has been wasted and transferred to another, unwanted energy store

Question 21

Describe the energy transfer when an electric kettle is used to heat water

Answer 21

the electric current in a kettle transfers energy to the heating element of the kettle - energy is then transferred from the heating elements of the kettle to the thermal energy store of the water

Question 22

Describe the energy transfer when a falling apple hits the ground

Answer 22

the energy from the apples gravitational store is mechanically transferred to its kinetic store and from its kinetic store its dissipated into the surroundings by sound waves

Question 23

What is a system?

Answer 23

An object or a group of objects

Question 24

What is a closed system?

Answer 24

A closed system doesn’t transfer or receive any energy from the surroundings. The total energy in a closed system never changes.