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OAT Physics
Chapter 3 - Work, E, and Momentum
Term | Definition |
---|---|
Work | F acting on an object which moves through a distance d; = Fd cos theta |
When F and d are perpendicular | No work is done cuz cos 90 = 0 |
Power | rate at which work is done; Watts = J/s |
Kinetic E | E of motion; = 1/2 mv^2 |
Potential E | E of position; = mgh |
When mechanical E is not conserved... | E is drained away in form of heat |
Mechanical E | KE + PE = total E |
W when is comes to mass and velocity | = change in KE |
Non-conservative Force | friction |
Conservation of E | when the work done by non-conservative forces is zero (no air resistance), E is conserved and E = KE + PE |
Pulleys | these allow F to be reduced but distance that the force is exerted over is increased to compensate |
Efficiency (Pulley) | W out/W in ; load x load distance/effort x effort distance |
effort distance | load distance multiplied by the number of pulleys present |
Momentum | p = mv |
Impulse | J = Ft = change in momentum |
Conservation of Momentum (collisions) | Total p initial = Total p final; (p of object a)(p of object b)i = (pa)(pb)f |
Completely inelastic collisions | objects stick together after the collision; only momentum conserved |
Completely elastic collisions | objects dnt stick together after collision; KE is conserved; use momentum AND KE equations here |
Center of Mass Equation | X = (m1x1 + m2x2) / m1 +m2; x is the center point of the object. If a cube has a length of 4m, x would be at 2m |