An object is undergoing uniform circular motion. Its speed is 10 m/s and the radius of its path is 15 m. When its speed is halved, its centripetal acceleration is
A) four times larger than the original centripetal acceleration.
B) twice as large as the original centripetal acceleration.
C) the same as the original centripetal acceleration.
D) half of the original centripetal acceleration.
E) a fourth of the original centripetal acceleration.

Question

Quizplus · Accepted Answer

The centripetal acceleration is given by $a_c = \frac{v^2}{r}$. When the speed is halved, the new speed is $v/2$, so the new acceleration is $\frac{(v/2)^2}{r} = \frac{v^2}{4r}$, which is a fourth of the original centripetal acceleration.

An Object Is Undergoing Uniform Circular Motion