Equations

Question 1

Speed

Answer 1

Speed(m/s)=Distance(m)/time(s)

Question 2

Acceleration

Answer 2

Acceleration(m/s2)= (final sped-initial speed)/time

Question 3

Force

Answer 3

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

Question 4

Weight

Answer 4

Weight(N)= mass(kg) x gravity(N/kg)

Question 5

Momentum

Answer 5

Momentum(kg m/s)= mass(kg) x velocity(m/s)

Question 6

Force (involving momentum)

Answer 6

Force(N)= change in momentum(kg m/s)/ time taken(s)

Question 7

Moment

Answer 7

Moment(Nm)= Force(N) x distance from pivot(m)

Question 8

Orbital speed

Answer 8

Orbital speed(km/s) = 2× π ×orbital radius(km)/time period(s)

Question 9

Power (electricity module)

Answer 9

Power(W)= current(A) x potential difference(V)

Question 10

Energy transferred

Answer 10

Energy transferred(J)= power (W) × time (s)
Energy transferred(J)= charge flow (C) × potential difference (V)

Question 11

Charge flow

Answer 11

Charge flow(C)= current(A) x time(s)
36000C= 36 kC

Question 12

Potential difference

Answer 12

Potential difference(V)= current(A) x resistance (ohm)

Question 13

Efficiency

Answer 13

Efficiency(%)=(useful energy transferred(J)/total energy transferred(J)) x 100

Question 14

Graviational potential energy

Answer 14

Gravitational potential energy(J) = mass(kg) x height (m) x gravitational field strength (N/kg)

Question 15

Work done

Answer 15

Work done(J)= Force(N) x distance(m)

Question 16

Power (energy resources module)

Answer 16

Power(W or J/s)= work done(J)/ time taken(s)

Question 17

Kinetic energy

Answer 17

Kinetic energy= 0.5 x mass(kg) x speed^2(m/s)

Question 18

Potential Energy

Answer 18

Potential energy=mass x height x gravity(force x distance)

Question 19

pressure in a solid

Answer 19

pressure (Pa) = force normal (N) / surface area (m2)

Question 20

pressure in a liquid

Answer 20

pressure(Pa) = height (m) x density of fluid (kg/m3) x gravtational field strength (10)

Question 21

density

Answer 21

density kg/m3 = mass (kg) / volume (m3)

Question 22

volume of a sphere

Answer 22

(4/3) x pie r3

Question 23

wave speed

Answer 23

wave speed (m/s) = wave length (m) x frequency (hz)

Question 24

(waves module) frequency

Answer 24

frequency (hz) = 1/time period (s)

Question 25

(waves module) time period

Answer 25

time period (s) = 1/ frequency (hz)

Question 26

snell’s law

Answer 26

n (refractive index) = sin(i)/sin(r)

Question 27

critical angle

Answer 27

sin(c) (critical angle) = 1/n (refractive index)

Question 28

pressure and volume at a constant temperature

Answer 28

P(1) x V(1) = P(2) x V(2)

Question 29

pressure and temperature at constant volume

Answer 29

P(1)/ T(1) = P(2)/T(2)

Question 30

Voltage and turns in transformers

Answer 30

V(p)/V(s) = N(p)/N(s)

Question 31

input power and out put power in transformers

Answer 31

V(p) x I(p) = V(s) x I(s)

Question 32

Power (energy)

Answer 32

Power (W)= Energy transferred (J) / Time taken (s)

Question 33

Efficiency 2

Answer 33

Efficiency(%)=(useful power output (W)/total power input(W) x 100

Question 34

Total resistance of two components

Answer 34

R total (ohms) = R1 + R2 sum of resistance of each component

Question 35

Power 2

Answer 35

power (W) = current^2 (amps) × resistance (ohms)

Question 36

Force - extension of an elastic object

Answer 36

force (N) = spring constant (N/m) × extension (m)