Friction does negative work on bus and positive work on passenger. Work done by friction equals 1250 J (mu = 0.5, F = 250N, d = 50m). Engine does all work P = M(B+me) * a * d
At small angles of attack, boundary layers remain attached with minimal pressure gradients. At higher angles of attack, pressure drag becomes dominant over viscous drag. Streamlined bodies have lower resistance than bluff bodies for given area and velocity
Frictional force opposes motion between contacting surfaces. Force depends on surface texture and amount of applied force. Frictional force equals object's weight when flat. Unit is Newton (N) with dimensions [M L T-2]
Conservative forces do work independent of path taken. Gravity is an example of conservative force. Air resistance is an example of non-conservative force
Rolling motion combines rotational and translational motion observed daily. Static friction prevents wheels from slipping while rolling. Velocity of center of mass equals radius times angular velocity. Linear acceleration equals radius times angular acceleration. Distance traveled equals radius times angular displacement
Friction resists motion between contacting surfaces. Friction reduces mechanical advantage of machines. Automobiles use one-quarter of energy on limiting friction. Friction affects matches, machines, and molecular structures