11. A boy on a 2.0 kg skateboard initially at rest tosses an 8.0 kg jug of water forward. If the jug has a speed of 3.0 m/s relative to the ground and the boy and skateboard move in opposite directions at 0.60 m/s, find the boy’s mass.

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