Combined Physics 5086 Formulae List

1 Science(Physics) 5086 List of Formulae 1. Measurement Corrected reading = Observed reading – (Zero error) 2. Kinematics t dv= v: speed [m/s] or [ms-1] d: distance [m] t: time [s] timetotal distance totalspeed Average = Average speed [m/s] total distance [m] total time [s] t uva −= a: acceleration [m/s2] or [ms-2] v: final velocity [m/s] t: time taken [s] u: initial velocity [m/s] Distance travelled = Area under Speed-Time graph 4. Forces & Pressure mgW= W: weight [N] m: mass [kg] g: acceleration due to gravity [m/s2] V mρ= ρ : density [kg/m3] m: mass [kg] V: volume [m3] volumetotal mass totaldensity Average = Average density [kg/m3] total mass [kg] total volume [m3] A Fp= p: pressure [Pa] or [N/m2] F: force [N] A: area [m2] 4. Forces and Pressure maFR = FR: resultant or net force [N] m: mass [kg] a: acceleration [m/s2] 5. Turning Effect of Forces M = F d M: moment of a force about a pivot [Nm] F: force [N] d: perpendicular distance from the line of action of the force to the pivot [m] Principle of moments: Sum of Anti-clockwise Sum of Clockwise Moments Moments F1 d1 + F2 d2 = F3 d3 + F4 d4 6. Energy, Work and Power GPE = mgh GPE: gravitational potential energy [J] m: mass [kg] g: acceleration due to gravity [m/s2] h: height raised [m] 2mv2 1KE= KE: kinetic energy [J] m: mass [kg] v: speed [m/s] W = F s W: Work done [J] F: force [N] s: distance moved in the direction of the force [m] t WP= or t FsP = or t EP= P: power [W] W: work done [J] E: energy [J] t: time [s] 7. Kinetic Model of Matter 8. Thermal Processes 9. General Wave Properties T 1=f f: frequency [Hz] T: period [s] F1 d1 F4 F2 d3 F3 = d2 d4

2 Wave velocity equation: f=v v: speed of wave [m/s] f: frequency [Hz]  : wavelength [m] Reflection of Sound: For determination of speed of sound using echo method: t 2dv= v: speed of sound [m/s] d: one-way distance [m] t: time taken for echo to be received [s] 10. Electromagnetic Spectrum 11. Light Angle of incidence = Angle of reflection Snell’s Law: r i sin sinη= or 1 1 2 2η sin η sinθθ= η : refractive index of a medium i: angle of incidence (in the vacuum or air) [o] r: angle of refraction (in the medium) [o] v cη= η : refractive index of a medium c: speed of light in vacuum or air = 3.0  108 m/s v: speed of light in the medium [m/s] 15. Electric Charge & Current Electricity Q = I t Q: charge [C] I: current [A] t: time [s] Q Wε= ε : electromotive force, e.m.f. [V] W: work done [J] Q: charge [C] Q WV= V: potential difference, p.d., or voltage [V] W: work done or energy converted [J] Q: charge [C] Ohm’s Law: IRV= V: potential difference, p.d., or voltage [V] I: current [A] R: resistance [Ω] AρR l= R: resistance [Ω] ρ : resistivity [Ωm] l: length [m] A: cross-sectional area [m2] 13. D.C. Circuits Effective resistance, Reff [Ω], for resistors in series: Reff = R1 + R2 + R3 + … + Rn Effective resistance, Reff [Ω], for resistors in parallel: 1 1 2 3 n 1 1 1 1 ...R R R R effR − = + + + +  Applying principle of current in a parallel circuit, IA = IB + IC = ID Applying principle of p.d. in a series circuit, ε = V1 + V2 + V3 Applying principle of p.d. in a parallel circuit, V2 = V4 + V5 d R1 R2 R3 Rn R1 R2 R3 Rn V1 V3 V2 V4 V5 IA IB ID IC

3 14. Practical Electricity R VRIIVP 2 2 === P: power [W] I: current [A] V: voltage [V] R: resistance [Ω] PtE= E: electrical energy [J] P: power [W] t: time [s] For calculating cost of using electricity, PtE= E: electrical energy [in kWh] P: power [in kW] t: time [in hour] Cost = Electrical energy x Cost per unit 15. Magnetism and Electromagnetism 16. Radioactivity