R= mg cos a + Psin a Note: If the surface is smooth, then F=0
Examples
. A body of mass 5 kg rests on an inclined
plane whose angle of inclination to the
horizontal can be varied. If the coefficient of
friction between the body and the surface of
the inclined plane is 0.3, at what angle does
the body start to slide down from the plane?
Solution
RR
D

A150 w lamp emits light of wavelength 590 nm uniformly in all directions. what is the photon flux (photons per unit area per unit time) on a small screen at a distance 2.3 m from the lamp? assume the photons are uniformly distributed over the surface of a sphere of radius 2.3 m.

Suppose water is leaking from a tank through a circular hole of area ah at its bottom. when water leaks through a hole, friction and contraction of the stream near the hole reduce the volume of water leaving the tank per second to cah 2gh , where c (0 < c < 1) is an empirical constant. a tank in the form of a right-circular cone standing on end, vertex down, is leaking water through a circular hole in its bottom. (assume the removed apex of the cone is of negligible height and volume.) (a) suppose the tank is 20 feet high and has radius 8 feet and the circular hole has radius 2 inches. the differential equation governing the height h in feet of water leaking from a tank after t seconds is dh dt = − 5 6h3/2 . if the height of the water is initially 8 feet, how long will it take the tank to empty? (round your answer to two decimal places.)

Astudent pushes a 60-n block across the floor for a distance of 10 m. how much work was done to move the block