Which have the same velocity? A, a boy walking east at 2 km/h and a man
walking east at 4 km/h
B. a car standing still and a truck driving in a
circle at 4 km/h
C. a dog walking west at 3 km/h and a cat
walking west at 3 km/h
D. a girl walking west at 3 km/h and a boy
walking south at 3 km/h

(a) assume the equation x = at^3 + bt describes the motion of a particular object, with x having the dimension of length and t having the dimension of time. determine the dimensions of the constants a and b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.) (b) determine the dimensions of the derivative dx/dt = 3at^2 + b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.)

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?

How does an observation about an object differ from an inference about that object