all equations

Question 1

speed

Answer 1

speed (m/s) = distance (m) / time (s)
d
s t

Question 2

acceleration

Answer 2

acceleration = change in velocity ( final velocity (m/s) - starting velocity (m/s)) / time
v-u
a t

Question 3

force

Answer 3

force (N) = mass (Kg) x acceleration (m/s^2)
F
m a

Question 4

weight

Answer 4

weight (N) = mass x gravitational field strength (m/s^2)
w
m g

Question 5

energy transferred

Answer 5

work done

Question 6

efficiency

Answer 6

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

Question 7

density

Answer 7

density (kg/m^3) = mass (kg) / volume (m^3)
p
m V

Question 8

gradient

Answer 8

change in distance / change in time

gradient of a distance/time = speed

Question 9

in a speed-time graph, how do you find the distance?

Answer 9

the area under the line is the distance travelled

1/2 x base x height

Question 10

how do you find the acceleration from a speed-time graph?

Answer 10

the gradient of the line

Question 11

what is gravity equal to in acceleration?

Answer 11

10m/s^2

Question 12

momentum

Answer 12

mass x velocity
m
m v

Question 13

work done

Answer 13

force x distance moved

Question 14

kinetic energy

Answer 14

1/2 x mass x speed^2

Question 15

gravitational potential energy

Answer 15

mass x g x height

Question 16

pressure

Answer 16

force / area

Question 17

moment

Answer 17

force x perpendicular distance from the pivot

Question 18

charge

Answer 18

current x time

Question 19

voltage

Answer 19

current x resistance

Question 20

electrical power

Answer 20

voltage x current

Question 21

wave speed

Answer 21

frequency x wavelength

Question 22

turns and voltage for a transformer

Answer 22

input (primary) voltage/output (secondary) voltage = primary turns/secondary turns

Question 23

refractive index, angle of incidence and angle of refraction

Answer 23

n = sin i / sin r
i = incidence 
r = refraction

Question 24

refractive index and critical angle

Answer 24

sin c = 1 / n

Question 25

pressure difference

Answer 25

height x density x gravitational field strength

Question 26

input power = output power

Answer 26

Vp Ip = Vs Is