A wind-up radio is used in places where mains electricity is unavailable. A person turns a handle to wind a spring inside the radio. As the spring unwinds, it causes a small coil to rotate in a magnetic field. Which energy transfer is not useful for this radio?
- Aelastic potential energy $\rightarrow$ kinetic energy
- Bkinetic energy $\rightarrow$ thermal energy
- Cchemical energy $\rightarrow$ elastic potential energy
- Dkinetic energy $\rightarrow$ sound energy