Enough Physics to Help You Get By

Equations

Project 1      

Project 2       d = d_o + vt

Project 3       d = d_o + v(t – t_o)

Project 5       F = ma

Project 8      

Project 9       v = R / t

          R = (v²/g)sin 2 θ

          h = (v sin θ)²/2g

Project 10     v_x = R/t

Project 13      

Project 17       v = √rg

Project 19       g = 2d/t²

              a = 2d/t²

Project 22      

Project 31      

Project 51      

Project 56      

Project 67      

Project 68      

Project 70       f = v/2(L + 0.8d)

Project 77      

            v = 331 + 0.6T

Project 81       I = I_o/r²

Project 83      

Project 85       n_i sin (θ_i) = n_r sin (θ_r)

Project 86       I/I_o = cos² θ

Project 96      

Project 100       Ohm's law

            V = RI

            R = VI, and I = V/R

            R_series = R₁ + R₂

            1/R_parallel = 1/R₁ + 1/R₂ + …

Project 103     The current for a charging capacitor is given by I = I_oe–^t/RC

            The voltage for a charging capacitor is given by V = V_o(1 – e–^t/RC)

            The current for a discharging capacitor is given by I = I_oe–^t/RC

            The voltage for a discharging capacitor is given by V = V_oe–^t/RC

Project 116       I = I^oe^qV/kT

Project 121       E_photon = hf

Project 125      

Units used in this book

Length

1 m = 3.28 ft

1 mile = 1.61 km

1 inch = 2.54 cm

Time

1 day = 86,400 s

1year (365¼ days) = 3.16 × 10⁷ s

Energy and Power

1 J = 0.738 ft-lb = 0.239 cal

1 kW-hr = 3.6 × 10⁶ J

1 W = 1 J/s

1 hp = 746 J

Force

1 N = 0.225 lb

1 lb = 4.45 N

Weight and mass

A 1 kg mass has a weight of 9.8 N (on Earth)

A 1 kg mass has a weight of 2.2 lbs (on Earth)

Speed/velocity

1 m/s = 2.24 mi/hr

1 km/hr = 0.621 mi/hr

1 km/hr = 0.278 m/s = 0.91 ft/s

Volume

1 cc = 1 cm³ = 1 mL

1 liter (l) =1000 cm³

1 gal = 3.79 liters

Pressure

1 Pa = 1 N/m² =1.45 × 10–⁴ lb/in²

1 atm = 1.01 × 105 Pa

= 14.7 lb / in² (psi)

= 760 mm-Hg

= 760 torr

Examples of prefixes

1 km = 1000 m

1 kg = 1000 g

1 m = 100 cm = 1000 mm

1 liter = 1000 mL

1 μm = 1 × 10–⁶ meter

1 nm = 1 × 10–⁹ meter

1 megohm = 1 × 10⁶ ohm