Equations

Question 1

density, mass, and volume

p = ( )

Answer 1

density= mass/ volume
p=m/V

Question 2

Speed

average speed= ( )

Answer 2

average speed= distance moved/ time taken

Question 3

acceleration

a = ( )

Answer 3

average acceleration= change in velocity/ time taken
a= v-u/ t

Question 4

force, mass, and acceleration

F = ( )

Answer 4

force= mass x acceleration
F= ma

Question 5

weight

W= ( )

Answer 5

weight= mass x g
W= mg

Question 6

moment of a force

moment of force about a point = ( )

Answer 6

moment of a force about a point= force x perpendicular distance from point

Question 7

stretched spring

F = ( )

Answer 7

load= spring constant x extension
F= kx

Question 8

pressure and force
p = ( )

Answer 8

pressure= force/ area
p= F/A

Question 9

pressure in a liquid

p = ( )

Answer 9

pressure= density x g x depth
p= pgh

Question 10

temperature

kelvin temperature = ( )

Answer 10

kelvin temperature= temperature in degrees celsius + 273

Question 11

compressing gases

Answer 11

for a fixed mass of gas at constant temperature:

pressure₁ x volume₁= pressure₂ x volume₂

p₁V₁= p₂V₂

Question 12

heating gases

Answer 12

for a fixes mass of has at constant volume:
pressure₁/ Kelvin temperature₁ = pressure₂/ Kelvin tempterature₂

p₁/T₁= p₂/T₂

Question 13

Work

W= ( )

Answer 13

Work done= force x distance moved in the direction of force

W= Fd

Question 14

Gravitational Potential energy

PE = ( )

Answer 14

gravitational potential energy=
mass x gravity x height

PE= mgh

Question 15

Kinetic energy

KE = ( )

Answer 15

kinetic energy= 1/2 x mass x velocity²

KE= 1/2mv²

Question 16

Energy and temperature change

E = ( )

Answer 16

energy transferred= mass x specific heat capacity x temperature change

E= mc▵T

Question 17

Energy and state change

E = ( )

Answer 17

energy transferred= mass x specific latent heat

E=mL

Question 18

Power

power = ( )

Answer 18

power= work done/ time taken= energy transformed/time taken

Question 19

Efficiency

Answer 19

Efficiency=
useful work done/ total energy input=
useful energy out put/total energy input=
useful energy output/total energy input

Question 20

waves

v = ( )

Answer 20

speed= frequency x wavelength

v = f λ

Question 21

frequency and period

f = ( )

Answer 21

frequency= 1/ period

f= 1/T

Question 22

refraction of light

n = ( )

Answer 22

refractive index= sine of angle of incidence/sine of angle of refraction

n= sine i/ sine r

Question 23

Total internal reflection

sin c = ( )

Answer 23

sine of critical angle= 1/ reflective index

sin c= 1/n

Question 24

charge and current

Q = ( )

Answer 24

charge= current x time

Q=It

Question 25

resistance, PD (voltage), and current R = ( )

Answer 25

Resistance= PD/ current R= V/I

Question 26

Resistors in series/parallel

Answer 26

series= R= R₁ + R₂ parallel= 1/R= (1/R₁) + (1/R₂)

Question 27

Electrical power P = ( )

Answer 27

Power= PD x current P= VI

Question 28

Electrical energy E = ( )

Answer 28

energy transformed= power x time = PD x current x time E = Vlt

Question 29

Transformers

Answer 29

output voltage/input voltage = output turns/input turns V₂ / V₁= n₂ / n₁

Question 30

for 100% efficient transformer

Answer 30

power input=power output V₁ I₁ = V₂ I₂