Formulas for Test 3

Test 3 will cover homeworks 10 to 15 (i.e. Chaps. 15, 16, 17, 19, 20, 21)

Speed or velocity = change in distance/change in time, v = d/t [Units: m/s]

Acceleration = change in velocity/change in time, a = (vf - vi)/t [Units: m/s/s or m/s2]


For acceleration under gravity (starting from rest at time t = 0s): g = 10m/s2

v = gt

d = 0.5gt2                                                        


Newton's second law of motion

Net force, Fnet = ma [Units: N]


Weight, W = mg [Units: N]

Momentum, p = mv [Units: kg m/s]      

Impulse = Fnett = change in momentum = pf - pi

Kinetic energy, KE = 0.5mv2 [Units: J]

Gravitational potential energy, GPE = mgh [Units: J]     

Work, W = Fd [Units: J]

Gravitational force, F = GM1M2/r2 [Units: N]

For molecules at a particular temperature T, KE = 0.5mv2 = 3kBT/2

Heat energy, Q = mcDT [Units: J]

Heat energy, Q = mL [Units: J]

Wave speed, v = fl [Units: m/s]

Wave frequency, f = 1/T where T is the period in seconds [Units for frequency: Hz = 1/s]



Quantities and units (in brackets)

distance, d (m)

time, t (s)

speed, v (m/s)

acceleration, a (m/s2), g (m/s2)

force, F (N); weight W(N)

mass, m (kg)

momentum, p (kg m/s)                                     

energy, KE, GPE (J)

work, W (J)

heat, Q (J)

specific heat capacity, c (J/kg C)

latent heat, L (J/kg)

temperature, T (C or K)

frequency, f (Hz or 1/s)

wavelength, l (m)




Speed of sound in air = 330m/s

Speed of light in a vacuum (or in air) = 3 x 108m/s = 300,000,000 m/s