El paquete de 50 lb que se muestra en la figura parte desde el reposo, se desliza hacia abajo sobre la rampa y es detenido por el resorte. El coeficiente de fricción cinético entre el paquete y la rampa es μk = 0.12. Si se desea que el paquete llegue al reposo a pulgadas del punto de contacto, que valor debe tener la constante k del resorte?.

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