An astronaut in an orbiting space craft attaches a mass m to a string and whirls it around in uniform circular motion. the radius of the circle is r, the speed of the mass is v, and the tension in the string is f. if the mass, radius, and speed were all to double the tension required to maintain uniform circular motion would be

Athin nonconducting rod with a uniform distribution of positive charge q is bent into a circle of radius r. the central perpendicular axis through the ring is a z-axis, with the origin at the center of the ring. a) what is the magnitude of the electric field due to the rod at z = 0? n/c (b) what is the magnitude of the electric field due to the rod at z = infinity? n/c (c) in terms of r, at what positive value of z is that magnitude maximum? r (d) if r = 4.00 cm and q = 9.00 µc, what is the maximum magnitude? n/c