Physics Equations: Mechanics

Mechanics

• Frictional force (F) is equal to the coefficient of friction (μ) times the newtons (N): F = μN
• Force (F) times distance (D) is equal to force (F) times distance (D): F1D1 = F2D2
• Velocity (v) is equal to original velocity (vo) plus acceleration (a) times time (t): v = vo + at
• Displacement (s) is equal to original velocity (vo) times time (t) plus 0.5 times acceleration (a) times time (t) squared: s = vot + 0.5at^2
• Final velocity (v) is equal to the square root of initial velocity (vo) squared plus 2 times acceleration (a) times displacement (s): v = sqrt(vo^2 + 2as)

Energy

• Kinetic energy (K.E.) is equal to 0.5 times mass (m) times velocity (v) squared: K.E. = 0.5mv^2
• Potential energy (P.E.) is equal to mass (m) times gravity (g) times height (h): P.E. = mgh
• Potential energy (P.E.) is equal to 0.5 times spring constant (k) times compression (x) squared: P.E. = 0.5kx^2
• Momentum (ρ) is equal to mass (m) times velocity (v): ρ = mv
• Force (F) is equal to mass (m) times acceleration (a): F = ma
• Work (W) is equal to force (F) times distance (s): W = Fs

Ergonomic (Revised NIOSH Lifting Equations)

• Lifting Index (LI) is equal to object weight (L) divided by recommended weight limit (RWL): LI = L / RWL
• Recommended weight limit (RWL) is equal to load constant (LC) times horizontal multiplier (HM) times vertical multiplier (VM) times distance multiplier (DM) times asymmetric multiplier (AM) times frequency multiplier (FM) times coupling multiplier (CM): RWL = LC × HM × VM × DM × AM × FM × CM

Heat Stress and Relative Humidity

• Indoor heat stress is calculated by: 0.7WB + 0.3GT
• Outdoor heat stress is calculated by: 0.7WB + 0.2GT = 0.1DB

Concentrations of Vapors and Gases

• Parts per million (ppm) is equal to measured mg/m3 of contaminant divided by molecular weight (MW) of contaminant: ppm = mg/m3 / MW
• Threshold limit value (TLV) of a chemical is equal to the sum of fractions of chemicals in the mixture: TLV = f1TLV1 + f2TLV2 + ... + fnTLVn

Ventilation

• Volumetric flow rate (Q) is equal to velocity (V) times cross-sectional area (A): Q = VA
• Velocity (V) is equal to 4005 times coefficient of entry loss (Ce) times static pressure of the hood (SPh): V = 4005CeSPh
• Static pressure of the hood (SPh) is equal to velocity pressure (VP) plus hood entry loss (he): SPh = VP + he

Engineering Economy

• Future value of money (F) is equal to present value of money (P) times (1 + interest rate (i)) to the power of number of years (n): F = P(1 + i)^n
• Present value of money (P) is equal to future value of money (F) divided by (1 + interest rate (i)) to the power of number of years (n): P = F / (1 + i)^n

Reliability

• Probability of failure (Pf) is equal to 1 minus reliability (R): Pf = 1 - R
• Reliability (R) is equal to e to the power of (-λt): R = e^(-λt)

Noise

• Sound intensity (I) is equal to sound pressure level (p) squared divided by the density of the medium (ρ) times the speed of sound (c): I = p^2 / (ρc)
• Sound pressure level (Lp) is equal to 20 times the logarithm of the measured sound pressure level (p) divided by the reference sound pressure level (po): Lp = 20log(p/po)

Radiation

• Ionizing radiation: intensity of source (I) is equal to initial intensity (Io) divided by the distance from the source squared: I = Io / d^2
• Nonionizing radiation: power density (W) is equal to antenna power (P) divided by the effective antenna area (A) times the distance from the antenna (d) squared: W = P / (A*d^2)

Review key equations in mechanics, including friction, force, velocity, and acceleration. Test your understanding of these fundamental concepts in physics.