Apuck is sliding on a frictionless, level surface in a circle at a constant speed. the required inward acceleration is provided by a spring of force constant k and unstretched length l0. in order to provide the needed force, the spring is stretched a distance ∆l.
~v
as the puck of mass m goes through a complete circle, how much work does the spring do on it?

Sally turns on her cellular telephone to speak to her friend who is located thousands of miles away. which of the following best describes how such a telephone is able to transmit and receive information? a. the cellular telephone transmits, receives, and encodes information using only sound waves. b. the cellular telephone transmits, receives, and encodes information using only electromagnetic waves. c. the cellular telephone transmits information by electromagnetic waves to a receiver which then encodes them and produces sound. d. the cellular telephone transmits information by sound waves to a receiver which then encodes them and produces electromagnetic waves.