Goals

• Understand that uncertainty is more realistically modeled by statisical models.
• Be able to compute Gaussian probablities using a transform table.

Tolerances

• Nominal sizes are note exact sizes
• Tolerance limits are specified as absolutes
• Tight tolerances = higher costs
• Dimensioning should include the minimum non-redudant info
• Dimensions should be chosen based on part functionality
• Tolerance stackup

Units

• We will be using two unit system: International System of Units and U.S. Customary Units
• US, Liberia, Burma only countries that use the U.S. system.
• F = MLT^{-2}

M = FT^2 / L = (pound-force) (second)^2 = lbf * s^2 / ft = slug

• lbf: pound force
• kip : kilo pounds force

F = ML / T^2 = (kilogram) (meter) / (second)^2 = kg m / s^2 = N

W = mg

g = 9.81 m/s^2 = 32.2 ft/s^2

• Mars climate orbiter: https://en.wikipedia.org/wiki/Mars_Climate_Orbiter
• Cost about $600 million
• output lbf s instead of N s

Sig figs

• sig figs are inferred by shown digits (except leading): 0.700"
• scientific notation: 706.0, 7.060x10^2, 0.7060x10^3, 7.060E2
• the smallest sig figs in a calc fix the number of sig figs you should report
• do all calcs at greatest accuracy possible and round at the end