At one particular moment, a 15.0 kg toboggan is moving over a horizontal surface of snow at 4.80 m/s. after 7.00 s have elapsed, the toboggan stops. use a momentum approach to find the magnitude of the average friction force (in n) acting on the toboggan while it was moving

Consider a uniformly charged ring in the xy plane, centered at the origin. the ring has radius a and positive charge qdistributed evenly along its circumference. a)what is the direction of the electric field at any point on the z axis? . b)what is the magnitude of the electric field along the positive z axis? use k in your answer, where k=14πϵ0. d)the ball will oscillate along the z axis between z=d and z=−d in simple harmonic motion. what will be the angular frequency ω of these oscillations? use the approximation d≪a to simplify your calculation; that is, assume that d2+a2≈a2. express your answer in terms of given charges, dimensions, and constants