# Physics

posted by
**Sam**
.

A model airplane is flying in a horizontal circle with a constant speed. The initial radius of the circle is R. The boy holding the cord to which the airplane is attached, then decides to increase the length of the cord so that the radius of the circle increases to 2R. The speed of the airplane does not change. How does the final centripetal acceleration of the airplane when the radius is 2R compare to the initial centripetal acceleration of the airplane when the radius is R?

The final centripetal acceleration is one-fourth the initial centripetal acceleration.

The final centripetal acceleration is two times the initial centripetal acceleration.

The final centripetal acceleration is four times the initial centripetal acceleration.

The final and the initial centripetal accelerations have the same value.

The final centripetal acceleration is one-half the initial centripetal acceleration.