You are pushing a 30-kg block on a rough floor in a direction that is parallel to the floor. The block moves with a uniform 2 m/s velocity. If your normal force on the block is 200 N, what is the magnitude of the friction force?

Afisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. it takes a time of 2.20 s for the boat to travel from its highest point to its lowest, a total distance of 0.670 m . the fisherman sees that the wave crests are spaced a horizontal distance of 5.80 m apart. (a) how much is the wavelength? (b) find the period of the wave. (c) how fast are the waves traveling? (d) what is the amplitude a of each wave?