physics
posted by Sam .
A cup of coffee is on a table in an airplane flying at a constant altitude and a constant velocity. The coefficient of static friction between the cup and the table is 0.18. Suddenly, the plane accelerates forward, its altitude remaining constant. What is the maximum acceleration that the plane can have without the cup sliding backward on the table?

A 301kg motorcycle is accelerating up along a ramp that is inclined 30.0º above the horizontal. The propulsion force pushing the motorcycle up the ramp is 3420 N, and air resistance produces a force of 230 N that opposes the motion. Find the magnitude of the motorcycle's acceleration.

ma=F(fr) =μ•N = μ•m•g.
a= μ •g = 0.18•9.8=1.764 m/s².