Which of the following situations is an example of a mostly elastic collision? A. Two billiard balls collide and bounce off each other.
B. Two train cars collide and stick together.
C. When a soft piece of clay falls onto the floor, its shape flattens.
D. A glass falls off the table and breaks.

(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.)