Formulae

Question 1

state the equation linking average speed, distance and time

Answer 1

average speed(m/s) = distance(m) ÷ time(s)

Question 2

state the equation linking force, mass and accelaration

Answer 2

force (N) = mass (kg) x acceleration (m/s²)

Question 3

state the equation linking acceleration, velocity and time

Answer 3

acceleration(m/s²) = change in velocity(m/s) ÷ time taken(s)

Question 4

state the equation linking density, mass and volume

Answer 4

density (g/cm³) = mass(g) ÷ volume(cm³)

Question 5

state the equation linking force, distance and work done

Answer 5

work done(J) = force(N) x distance moved in direction of force(m)

Question 6

state the equation linking mass, weight and gravitational field strength

Answer 6

weight(N) = mass(kg) x gravitational field strength(N/kg))

Question 7

state the equation linking pressure, force and area

Answer 7

pressure(N/cm²) = force(N) ÷ area(cm²)

Question 8

state the equation linking moment of a force and distance from pivot

Answer 8

moment(Nm) = force(N) x perpendicular distance from pivot(m)

Question 9

state the equation linking charge, current and time

Answer 9

charge(C) = current(A) x time(s)
or
Q=IT

Question 10

state the equation linking voltage, current and resistance

Answer 10

voltage(V) = current(A) x resistance(Ω)
or
V=IR

Question 11

state the equation linking power, current and voltage

Answer 11

power(W) = current(A) x voltage(V)
or
P=IV

Question 12

state the equation linking wave speed, frequency and wavelength

Answer 12

wave speed(m/s) = frequency(Hz) x wavelength(m)

Question 13

state the equation for the refractive index

Answer 13

n = sin(i) ÷ sin(r)

Question 14

state the equation for the critical angle

Answer 14

sin(c) = 1 ÷ n

Question 15

state the equation for pressure difference

Answer 15

pressure difference(Pa) = height(m) x density(kg/m³) x g(N/kg)

Question 16

state the equation for efficiency

Answer 16

efficiency = useful energy output ÷ total energy input

Question 17

state the equation for gravitational potential energy

Answer 17

GPE(J) = mass(kg) x height(m) x gravitational field strength(N/kg)

Question 18

state the equation for kinetic energy

Answer 18

KE(J) = 1/2 x mass(kg) x speed²(m/s)

Question 19

state the equation for energy transferred and work done

Answer 19

energy transferred = work done

Question 20

state the equation linking momentum, mass and velocity

Answer 20

momentum(kgm/s) = mass(kg) x velocity(m/s)

Question 21

state the equation linking voltage, energy and charge

Answer 21

voltage(V) = energy(J) ÷ charge(C)

Question 22

state the transformer relationship between voltage and turns

Answer 22

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

Question 23

state the transformer relationship for 100% efficiency

Answer 23

input power = output power

V1 x I1 = V2 x I2

Question 24

state the equation linking energy transferred, current, voltage and time

Answer 24

energy transferred(J) = current(A) x voltage(V) x time(s)
or
energy transferred (J) = power (W) x time(s)

Question 25

state the equation for frequency

Answer 25

frequency(Hz) = 1 ÷ time period(s)

Question 26

state the principle of conservation of momentum

Answer 26

momentum after = momentum before

Question 27

state the equation linking work done, power and time taken

Answer 27

power(W) = work done(J) ÷ time taken (s)

Question 28

State the equation linking time taken, change in momentum and force

Answer 28

Force = change in momentum ÷ time taken

Question 29

state the equation linking pressure, volume and temperature for a gas

Answer 29

P1 x V1 = P2 x V2
T1 T2
NB: temperature MUST be in KELVINS