Equations

Question 1

Average speed

Answer 1

Average speed = Distance travelled / time taken

Question 2

acceleration

Answer 2

a = Δv / Δt
velocity / time taken

Question 3

Force

Answer 3

force = mass x acceleration

F = m x a

Question 4

Weight

Answer 4

Weight = mass x gravitational field strength.

W = m x g

Question 5

Power (E&M)

Answer 5

P = i x V

Power = Current x Pd

Question 6

Energy Transferred (E&M)

Answer 6

E = i x V x t
E = Q x V

Question 7

Voltage

Answer 7

V = i x R
V= W/Q
V = P/i
V = E/Q

Question 8

Charge

Answer 8

Q = I x t
Q = W/V
Q = E/V

Question 9

Wave speed

Answer 9

V = f x wavelength

Question 10

Density

Answer 10

p = m / v
Density = mass / volume

Question 11

Spring Constant

Answer 11

k = F/x
Spring constant = Force / extension

Question 12

Pressure

Answer 12

P = F/A
Pressure = Force / Area

Question 13

Moment

Answer 13

moment = F x d
Moment = Force x Perpendicular distance from pivot.

Question 14

Momentum

Answer 14

p = mv
Momentum = Mass x velocity

Question 15

Resultant Force

Answer 15

F = Δmomentum / Δt
F = change in momentum / change in time

Question 16

Impulse

Answer 16

impulse = F x Δt = Momentum

Question 17

Kinetic Energy

Answer 17

Ek = 1/2 MV^2
Kinetic energy = half mass x velocity^2

Question 18

Gravitational potential energy

Answer 18

ΔEp = MgΔh
ΔEp = Mass x gravity x change in height

Question 19

Work

Answer 19

W = F x d = ΔE
Work done (joules) = Force x distance moved = energy transferred

Question 20

Power

Answer 20

P = W/t
or
P = ΔE / t
Power = work done / time

Question 21

efficiency

Answer 21

efficiency = (useful energy output / total energy output) x 100%

Question 22

Change in pressure below the surface of a fluid

Answer 22

Δp = Density x g x Δh
Change in pressure = density x gravity x change in depth

Question 23

Orbital Period

Answer 23

T = 2πr / v
Orbital period = 2 x pi x radius / speed

Question 24

Specific Heat Capacity

Answer 24

C = ΔE / mΔT

T = temperature

Question 25

pV constant

Answer 25

P1 x V1 = P2 x V2

Question 26

Refractive Index

Answer 26

n = sin i / sin r
or
n = 1 / sinc c

i = angle of incidence
r = angle of refraction
c = critical angle

Question 27

Current

Answer 27

I = Q / t
current = charge / time

Question 28

Emf

Answer 28

E = W / Q
Emf = electrical work done / charge

Question 29

Potential Difference

Answer 29

V = W / Q
Pd = Word done (energy transferred) / charge

Question 30

Resistance

Answer 30

V = IR
or
R = V / I
resistance = volts / current

Question 31

Energy

Answer 31

E = PT
Energy = power x time

Question 32

Parallel Resistors

Answer 32

Rc = (R1xR2) / (R1 + R2)

Question 33

Turn Ratio

Answer 33

Vp / Vs = Np / Ns

Primary voltage / secondary voltage = Number of primary turns / number of secondary turns

Question 34

Half Life

Answer 34

amount of time it takes for half of a radioactive substance to decay

Question 35

Hubble Constant

Answer 35

H0 = v / d

H0 = 2.2 x 10^-18

v = receding speed of a galaxy
d = distance of the galaxy

Question 36

age of the universe

Answer 36

1 / H0

d / v = 1 / H0 = age of the universe