P1 Energy

Question 1

Gravitational potential energy

Answer 1

Energy stored in an object as a result of its position or height

Question 2

Formula for GPE

Answer 2

Ep = m * g * h

GPE(J) = mass(Kg) * GFS(N/Kg) * height(m)

Question 3

Formula for GFS

Answer 3

g = Fg / m

GFS(N/Kg) = weight(N) / mass(Kg)

Question 4

Gravitational field strength

Answer 4

Force experienced by a unit of mass due to the force of gravity at that position

Question 5

Energy stores

Answer 5

Captured quantities of energy for use at a later time

Question 6

Common energy stores

Answer 6

Nuclear
Chemical
GPE
EPE
Kinetic

Question 7

Formula for kinetic energy

Answer 7

Ek = 1/2(m * v^2)

Kinetic energy(J) = 1/2(mass(Kg) * velocity(m/s)^2)

Question 8

Formula for EPE stored

Answer 8

U = 1/2(k * e^2)

Elastic energy (J) = 1/2(spring constant(N/m) * extention(m)^2)

Question 9

Conservation of energy

Answer 9

Energy cannot be created or destroyed

It can only be transferred between energy stores

Question 10

Forms of energy transformation

Answer 10

Electrical work
Heating
Waves
Mechanical work

Question 11

Mechanical work

Answer 11

The displacement of an object due to the amount of mechanical energy transferred to it by a force

Question 12

Formula for mechanical work done

Answer 12

W = F * d

Work(J) = Force(N) * distance(m)

Question 13

Formula for mechanical power

Answer 13

P = W / Δt

Power(W) = Work(J) / time elapsed(s)

Question 14

Formula for electrical work done

Answer 14

E = V * I * t

Energy(J) = Potential difference(V) * Current(A) * time(s)

Question 15

Formula for electrical power

Answer 15

P = I * V

Power(W) = Potential difference(V) * Current(A)

Question 16

Formula for power using speed

Answer 16

P = F * v

Power(W) = Force(W) * velocity(m/s)

Question 17

Wasted energy

Answer 17

Energy transferred to unwanted energy stores and dissipated

Question 18

Friction

Answer 18

The resistance to motion of one object moving relative to another resulting in heat

Question 19

Efficiency

Answer 19

The amount of energy transferred to wanted energy stores

Question 20

Formula for efficiency

Answer 20

η = 100(P / E)

effiency(%) = 100(Useful output(“product” J) / Total energy(J))

Question 21

Methods for reducing unwanted energy transfer

Answer 21

Thermal insulation

Lubrication

Question 22

Thermal insulation

Answer 22

Prevents heat loss in homes through roofs, windows, walls and flooring

Loft insulation
Double glazing
Cavity wall insulation
Thickening walls
Carpeting

Question 23

Lubrication

Answer 23

Reduces frictional forces

Lubricating wheels
Lubricating cogs