We perform an experiment which involves two masses m and M connected by a string which we will consider to be massless. Mass m hangs over the edge of a table. The string passes over a pulley at the edge of the table and mass M sits on the table, such that it moves along the table without friction. (See figure.) The tension in the string is the force that the string exerts where it is connected to another object or to more string. It is generally true that the tension anywhere along the string is the same as the tension anywhere else in the string.
In this experiment the mass m is initially at rest and allowed to drop. Its position x is measured downward from its initial position. At various times, the position x and velocity v of mass m are measured and the results are recorded in the table which follows:
t(s) x (m) v (m/s)
0.0 0.00 0.0
0.2 0.01 0.1
0.4 0.04 0.2
0.6 0.09 0.3
What is the average velocity vavg for the interval of time shown in the table?