Physical World 1

Physical World 1 - 11.30am

Formulas for Test 4

Formulas (You may tear off this page.)

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/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, F_net = ma [Units: N]

Weight, W = mg [Units: N]

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

Impulse = F_nett = change in momentum = p_f - p_i

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 = 3k_BT/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]

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USEFUL DATA: Speed of sound in air = 330m/s, Speed of light in a vacuum (or in air) = 3 x 10⁸m/s

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Coulomb's Law (force between charged particles), F = kq₁q₂/r² [Units: N]

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

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

Ohm's Law, I = V/R [Units: A]

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

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SYMBOLS AND UNITS

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charge, q [Units: C]; resistance, R [Units: W]; voltage, V [Units: V]

temperature, T [Units: ^oC]; specific heat capacity, c [Units: J/^oC/kg]; latent heat, L [Units: J/kg]

wavelength, l [Units: m]; mass, m[Units: kg]