**Formulas for Test 4**

**Test 4
will cover homeworks 16 to 21 (i.e. Chaps. 22, 23,
24, 25, 26, 28, 29)**

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

Acceleration = change in velocity/change in time, a = (v_{f} - v_{i})/t [Units: m/s/s or m/s^{2}]

For acceleration under gravity (starting from rest at time t
= 0s): g = 10m/s^{2}

v = gt

d = 0.5gt^{2}

Net force, F_{net} = ma
[Units: N]

Weight, W = mg [Units: N]

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

Impulse = F_{net}t
= change in momentum = p_{f} - p_{i}

Kinetic energy, KE = 0.5mv^{2} [Units: J]

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

Work, W = Fd [Units: J]

Gravitational force, F = GM_{1}M_{2}/r^{2}
[Units: N]

For molecules at a particular temperature T, KE = 0.5mv^{2}
= 3k_{B}T/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]

Coulomb's Law (force between charged particles), F = kq_{1}q_{2}/r^{2} [Units: N]

Electrical potential energy, EPE = V q [Units: J]

Current, I = q/t [Units: A]

Ohm's Law, V = IR [Units: V]

Power, P = EPE/t = V I [Units: W = J/s]

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**Quantities and units
(in brackets)**

distance, d (m)

time, t (s)

speed, v (m/s)

acceleration, a (m/s^{2}), g (m/s^{2})

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

mass, m (kg)

momentum, p (kg m/s)

energy, KE, GPE, EPE (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)

voltage, V (V, volts)

charge, q (C, coulombs)

current, I (A, amps)

resistance, R (W, ohms)

power, P (W, watts)

*************************************************************************************

**USEFUL DATA:**

Speed of sound in air = 330m/s

Speed of light in a vacuum (or in air) = 3 x 10^{8}m/s
= 300,000,000 m/s