Arolling ball has 18 joules of kinetic energy and is rolling 3 m/s .find its mass

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

Acoil suspended freely, points in some direction when no current is passed through it . can you tell what will happen when a current is passed though it?

Achild has maximum walking speed of 1.6 m/s. what is the length of the child's legs? 0.26 m