Topic 1 Key Concepts of Physics

• What is the SI unit for length?

  Metre, m
• What is the SI unit for mass?

  Kilogram, kg
• What is the SI unit for time?

  Second, s
• What is the SI unit for electric current?

  Ampere, A
• What is the SI unit for temperature?

  Kelvin, K
• What is the SI unit for the amount of substance?

  Mole, mol
• What is the SI unit for electric potential difference?

  Volt, V
• What is the SI unit for frequency?

  Hertz, Hz
• What is the SI unit for force?

  Newton, N
• What is the SI unit for energy?

  Joule, J
• What is the SI unit for power?

  Watt, W
• What is the SI unit for pressure?

  Pascal, Pa
• What is the SI unit for electric charge?

  Coulomb, C
• What is the SI unit for electrical resistance?

  Ohm, Ω
• What is the SI unit for magnetic flux density?

  Tesla, T
• What are the prefixes for the following SI units: giga, mega, kilo, centi, milli, micro, and nano?

  • Giga (G): x 10^9 (1 billion)
  • Mega (M): x 10^6 (1 million)
  • Kilo (k): x times 10^3 (1 thousand)
  • Centi (c): x 10^{-2} (1 hundredth)
  • Milli (m): x times 10^{-3} (1 thousandth)
  • Micro (µ): x 10^{-6} (1 millionth)
  • Nano (n): x 10^{-9} (1 billionth)
• What is the equation for calculating distance?

  Distance = speed × time
• What does the equation a (m/s^2)= v - u/t (s)

  It represents acceleration.
• What does the equation F = ma represent?

  It represents the relationship between force, mass, and acceleration.
• What does the equation w = mg calculate?

  It calculates the weight of an object based on its mass and gravitational acceleration.
• What does the equation GPE(J) = m(kg)x g(10N/kg) x change in h (m)

  It represents the change in gravitational potential energy.
• What is the equation for kinetic energy?


  KE(J) = 1/2 x m(kg) x speed ^2 (m/s)
• What is the formula for efficiency?

  Efficiency = \( \frac{\text{useful energy output}}{\text{total energy input}} \)
• What is the equation for wave speed?

  Wave speed = \( v = f\lambda \)
• What does the equation \( v = \frac{x}{t} \) represent?

  It represents wave speed in terms of distance and time.
• What is the equation for work done?


  Work done = force × distance (moved in the direction of the force) = \( E = Fd \)
• What is the formula for power?

  Power = \( \frac{\text{work done}}{\text{time}} = \frac{\text{energy transferred}}{\text{time taken}} \)
• What does the equation for moment of force represent?

  Moment of force = force × perpendicular distance
• What is the equation for energy transferred in terms of charge and potential difference?

  Energy transferred = charge moved × pd = \( E = QV \)
• What is the equation for charge in terms of current and time?

  Charge = current × time = \( Q = It \)
• What is the relationship between voltage, current, and resistance?

  Voltage = Current × Resistance = \( V = IR \)
• What is the equation for electrical power?

  Electrical Power = current × pd = \( P = IV \)
• What is the alternative equation for electrical power in terms of current and resistance?

  Electrical power = current² × resistance = \( P = I^2R \)
• What is the equation for density?

  Density = \( \frac{\text{mass}}{\text{volume}} = \rho = \frac{m}{V} \)
• What is the equation for the force on a spring?

  Force on spring = spring constant × extension = \( F = k\Delta x \)
• What is the equation for pressure?

  Pressure = \( \frac{\text{force}}{\text{area}} = P = \frac{F}{A} \)
• What is the equation for energy transferred in terms of voltage and time?

  Energy transferred = \( IVt \)
• What is the relationship between primary and secondary voltage and turns in a transformer?

  pd across primary / pd across secondary = number of turns in primary / number of turns in secondary = \( \frac{V_p}{V_s} = \frac{N_p}{N_s} \)
• What is the equation for the power of a transformer?


  Power of primary = power of secondary = \( V_p \times I_p = V_s \times I_s \)
• What is the equation for change in energy in terms of mass and specific heat capacity?

  Change in energy = mass × specific heat capacity × temp change = \( \Delta Q = mc\Delta \theta \)