Physics mcat

Coulomb's Law

F = k(q1*q2)/r^2 [SI units: N]

Density (ρ)

Density = m/V [SI units: kg/m^3]

Current

The flow of electric charge, given by I = Q/t [SI units: ampère (A) = C/s]

Specific Gravity

Specific gravity = ρsubstance/ρwater [no units]; ρwater = 103 kg/m^3

Weight

Weight = ρgV [SI units: newtons]

Pressure

A scalar quantity defined as force per unit area: P = F/A [SI units: pascal = N/m^2]

Electric Field

The direction of current is the direction positive charge would flow, or from high to low potential.

Ohm's Law

V = IR [can be applied to entire circuit or individual resistors]

Resistance

Opposition to the flow of charge, R = ρL/A [SI Units: ohm (Ω)]

Pressure

P = pgh

Bernoulli's Equation

P + 1/2ρv^2 + ρgh = constant

Kirchhoff's First Law

At any junction within a circuit, the sum of current flowing into that point must equal the sum of current leaving.

Kirchhoff's Second Law

The sum of voltage sources equals the sum of voltage drops around a closed-circuit loop.

Electrical Potential Energy (U)

U = q∆V = qEd = kQq/r [SI units: J]

Electric Dipoles

p is the dipole moment (p = qd).

Series Circuits

Req = R1 + R2 + R3 + ...

Parallel Circuits

1/Rp = 1/R1 + 1/R2 + 1/R3 + ...

Electrical Potential

The amount of work required to move a positive test charge q from infinity to a particular point divided by the test charge: V = U/q [SI units: volt = J/C]

Power Dissipated by Resistors

P = IV = I^2R [SI units: watt (W)]

Capacitance

The ability to store charge per unit voltage, given by C = Q/V.

Energy Stored by Capacitors

U = 1/2QV = 1/2CV^2 [SI units: J]

Pascal's Principle

A change in pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and to the walls of the containing vessel.

Voltage (∆V)

Voltage = W/q = kQ/r [SI units: volt = J/C]