Consider a string with several rocks tied along its length at equally spaced intervals. You whirl the string overhead so that the rocks follow circular paths. Compared with a rock at the end of the string, a rock at the middle moves
A)half as fast.
B)twice as fast.
C)at the same linear speed.

Question

Quizplus · Accepted Answer

In circular motion, the linear speed of a point is directly proportional to the distance from the center of rotation. The rock at the end of the string travels the circumference of a larger circle than the rock in the middle, so it covers a greater distance in the same time, making it move faster. The rock at the middle of the string has a smaller distance to travel, so it moves less per unit time than the rock at the end of the string, making it move half as fast. Therefore, the correct choice is A).

Consider a String with Several Rocks Tied Along Its Length