27. A bicycle wheel on a repair bench can be accelerated either by pulling on the chain that
is on the gear or by pulling on a string wrapped
around the tire. The tire's radius is 0.38 m, while
the radius of the gear is 0.14 m. What force would
you need to pull on the string to produce the
same acceleration you obtained with a force of
15 N on the chain?

Aplane travels 1000 miles in 5 hours .what is the planes average speed?

Find the magnetic field a distance r from the center of a long wire that has radius a and carries a uniform current per unit area j in the positive z direction.

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?