Formulas

Question 1

Pressure

Answer 1

Pressure (Pa) = Force (N) / Area (m²)

Question 2

Density

Answer 2

Density = Mass / Volume

Question 3

Speed

Answer 3

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

Question 4

Velocity

Answer 4

Velocity (m/s) = Displacement (m) / time (s)

Question 5

Acceleration

Answer 5

Acceleration (m/s²) = Velocity (m/s) / time (s)

Question 6

Force

Answer 6

Force (N) = Mass (kg) * Acceleration (m/s²)

Force (N) = Mass (kg) * 9.8 m/s²

Question 7

Gravitational field strength

Answer 7

Gravitational field strength (N/kg) = Weight (N) / Mass (kg)

Question 8

Gravitational potential energy

Answer 8

Gravitational potential energy (J) = Mass (kg) * Gravity (9.8) * Height (m)

Question 9

Kinetic energy

Answer 9

Kinetic energy (J) = ½ * Mass (kg) * [velocity (m/s) ]²

Question 10

Pressure in liquids

Answer 10

Pressure in liquids (Pa) = Depth (m) * Density (kg/m³) * 9.8 N/kg (gravitational field strength)

Question 11

Momentum

Answer 11

Momentum (kgm/s) = Mass (kg) * Velocity (m/s)

Question 12

Impulse

Answer 12

Impulse (Ns) = Force (N) * Time (s)
Impulse (kgm/s) = Final momentum - Initial momentum

Question 13

Work

Answer 13

Work (J) = Force (N) * Distance (m)
Work (J) = Change in Energy (J)

Question 14

Power

Answer 14

Power (W) = Work (J) / Time (s)

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

Question 15

Moment/turning force

Answer 15

Moment/turning force (Nm) = Force (N) * Distance perpendicular from pivot (m)

Question 16

Energy efficiency

Answer 16

Energy efficiency (J) = (Useful energy output (J) / Energy input (J) ) * 100

Question 17

Spring Constant

Answer 17

Spring Constant (N/m) = Force (N) / Extension (m)

Question 18

Wave speed

Answer 18

Wave speed (m/s) = frequency (Hz) * Wavelength (m)

Question 19

Reflective angle law

Answer 19

Angle of incidence = Angle of reflection

Question 20

Refractive index

Answer 20

Refractive index = Speed of light in vacuum / speed of light in a substance

Refractive index = Sin (Angle of incidence) / Sin (Angle of reflection)

Refractive index = 1 / Sin (Critical angle)

Question 21

Critical angle

Answer 21

Critical angle = Sin-1 (1/ Refractive index)

Question 22

Current

Answer 22

Current (Amps) = Charge (Coulombs) / Time (seconds)

I = Q/t

Current (Amps) = Potential difference (Volts) / Resistance (ohms)

I = V/R
V = IR

Question 23

EMF

Answer 23

EMF (Volts) = Work done (J) / Charge (C)

Question 24

Power (electricity)

Answer 24

Power (W or J/s) = Current (Amps) * Potential difference (Volts)

Power (W or J/s) = Energy (J) / time (s)

P = IV
P = E/t
E/t = IV → E = IVt
P = IV, V = IR → P = I²R
I = V/R, P = IV → P = V²/R

Question 25

Energy (electricity)

Answer 25

Energy (J) = Power (Watt) * Time (s) (bc P = E/t) Energy (kWh) = P (kW) * Time (h)

Question 26

Series --> Voltage, current, resistance

Answer 26

(Series), Vtotal = V1 + V2 + V3 (Series) Itotal = I1 = I2 = I3 (Series) Rtotal = R1 + R2 + R3

Question 27

Parallel --> Voltage, current, resistance

Answer 27

(Parallel) Vtotal = V1 = V2 = V3 (Parallel) Itotal = I1 + I2 + I3 (Parallel) 1/Rtotal = 1/R1 + 1/R2 + 1/R3

Question 28

. vs x

Answer 28

. = Coming out of the page x = Going into the page

Question 29

Transformer formulas

Answer 29

Vp/Vs = Np/Ns VpIp = VsIs (Because power stays the same → Cannot be created or destroyed)

Question 30

Efficiency of transformers

Answer 30

Efficiency of transformers = Pout/ Pin = (IsVs / IpVp) * 100

Question 31

Beta particles

Answer 31

Beta particles = AZX → A+0Z+1Y + 0-1e

Question 32

Alpha particles

Answer 32

Alpha particles = XAZ → YA-4Z-2 + a42

Question 33

Gamma particles

Answer 33

Gamma particles = XAZ → YAZ + 00 Y

Question 34

Number of remaining nuclei (counts/s)

Answer 34

Number of remaining nuclei (counts/s) = Original amount (counts/s) / 2n (n = number of halflife’s occurred)

Question 35

Specific heat capacity - Formula

Answer 35

Specific heat capacity = (Change in energy) / (Mass * Change in temperature) Energy (Joules Mass (Kg) Temperature (degrees Celsius or Kelvin) Units of specific heat capacity = J/(kgK) or J/(KgC)

Question 36

Hubble constant

Answer 36

Hubble constant (H0) is the ratio of an objects speed in which it is moving away from earth, to its distance from earth. H0 = v/d v - receding speed (m/s) d - distance from earth (m) The numerical value of the hubble constant is 2.2 * 10⁻¹⁸ per second. (applies to all galaxies measured + can therefore be used to estimate the age of the universe)

Question 37

How it the age of the universe estimated?

Answer 37

H0 = v/d v = d/t --> t = d/v --> 1/H0 = d/v = t t = 1/ (2.2*10⁻¹⁸) = 4.5 *10¹⁷ seconds = 14 billion years