QUICK REVISION
FORMULAS 1. Formulas related to force: F = ma F = kx F = m(vf² - vi²/2S) F = mv/t F = md/t² F = m(vf - vi)/t F = Area × density × velocity² F = 1/2 mv²/d F = 1/2 Pv/d F = Power/velocity Fc = mv²/r Fc = mrw² Fc/2 = mv²/2r Fc = 2K.E/r F = Area × Stress F = pir² × stress F = YA × Strain F = YAl/L F = pressure × area F = change in momentum × time interval F = - 2mVx × Vx/2l F2 = F1/A1 × A2 F = qE F = kQ/r² F = ILB sintheta F = q (v × B) F = qE + q(v × B) 2. Formulas related to energy and work Fd = k.e mgh = 1/2 mv² E = 1/2 kx² E = Ve E = nhf E = nhc/lambda E = Pc K.e = hf - work function = hf - hf° = hf - hc/w° (here w° is cutt off wavelength) E = 1/2 Pv mv²/2r= Fc/2 K.E/r = Fc/2 K.E = Fc×/r/2 K.e = 1.5 KT E = VQ E = Power × time E = Fvt % loss in K.e = v1² - v2²/v1² × 100 % loss in P.e = h1² - h²/h1² × 100 Energy lost due to air friction(Fh) = 1/2mv² - mgh (when body is thrown upward) Energy lost due to air friction(FS) = mgh - 1/2mv² (when body is thrown downward) E = 1/2 CV² (capacitor) E = R × hc (R is Rydberg' constant) J = m-¹ × Js ms-¹ hf kalpha x rays = EL - Ek hf kbeta x rays = EM - Ek Binding energy = mass defect × c² W = Fd Costheta W = nmgh (when person is climbing stairs) W = n(m+m) gh (when person is climbing stairs with some load) W = 0mgh + 1mgh + 2mgh + 3mgh ....... (in case of stacking bricks. For ist brick h=0. For 2nd brick h=1. For 3rd brick h=2 and so on) W = Fd = PA × change in V W = Q - change in U Q = mc × change in T T/273.16 = Q/Q3 (Thermodynamic scale) W = I²Rt W = emf×charge W = VQ W = 1/2 lF W = YAl²/2L W = StressAl²/2Strain W = PressureAl²/2Strain W = Fl²/2Strain 3. Formulas related to Power P = Fv P = E/t P = n(mgh/t) P = Fd/t P = mv²/2t 4. Formulas related to distance, displacement, velocity and accelration d = vt d = at² d = (vf + vi/2) ×t d = 5t² (for distance in 'n' seconds) d = 5(2tn - 1) (for distance in 'nth' second) d = 1/2 mv²/F d = vit + 5t² d = v × underroot 2H/g d = vt = x°wt = x°2pi/T × t = x°2pift x = x° Sin wt x = x° Sin (underroot k/m) t vf = vi + at 2as = vf² - vi² 2as = (vi + at)² - vi² 2as = vf² - (vf - at) ² v = underroot Vfx² + Vfy² v = Power/Force v = 2×K.E/momentum (k.e = 1/2 Pv) v² = 2×Power×time/mass (P = mv²/2t) v = underroot 2as v = underroot gr (speed at highest point in a verticle circle) v = underroot 5gr (speed at lowest point in a verticle circle) v² = 2FS/m v² = 2E/m v² = 2Ve/m v = eBr/m (velocity of particle under action of magnetic force along circular path) v² = Force/Area.Density v = w underroot x°² - x² v = underroot k/m × underroot x°² - x² v = x°w (at mean position where x=0) v = x° underoot k/m v = v° underroot 1 - x²/x°² (for determining ratio b/w inst. Velocity and maxi. Velocity) v= x°2pif = x°2pi/T a = x°w² = x°w.w = vw = v.2pif Common velocity = m1v1/m1+m2 vi² = Rg/Sin2theta v = underoot Tension×length/mass V = 2pi ke²/nh (speed of e- in nth orbit) Vn = V/n v = nh/2pimr (lambda = 2pir and lambda=h/p) ma = kx a = kx/m (SHM) a = - gx/l (Simple pendulum) ac = v²/r 5. Formulas related to wavelength 'w' w = v/f w = 1/wave number w1 = 2l (when pipe is opened at both ends) w1 = 4l (when pipe is opened at one end) Delta w = Us/f (doppler shift) Wavelength for obs. = w - delta w = v/f - Us/f w = hc/Ve w = hc/E w = h/mv w = h/P as P = underroot 2mE so w = h/underroot 2mE (de Broglie wavelength) w = underroot 150/V A° (short method for de Broglie wavelength. This formula is applicable only for e-) 1/w = RH (1/p²-1/n²) Wmaxi/Wmini = n²/n²-p² (for determining ratio b/w maxi. Wavelength to mini. Wavelength for series of atomic spectrum) w = 2pir/n (n is no. of loops in a circle
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