Model airplane speed. A spring balance scale attached to a wire that holds a model airplan...

Model airplane speed. A spring balance scale attached to a wire that holds a model airplane on a circular path indicates the force F on the wire. The speed of the plane V, in m7sec, is given by , where m is the mass of the plane (in kilograms) and r is the length of the wire (in meters). What is the top speed of a 2-kilogram plane on an 18-meter wire if the force on the wire at top speed is 49 newtons?