Anegative charge of -0.550 μc exerts an upward 0.900-n force on an unknown charge that is located 0.300 m directly below the first charge. part a what is the value of the unknown charge (magnitude and sign)? express your answer with the appropriate units.

Which statement best explains why an object weight less on mercury than it does on earth

What are the factors that affect the resistance of a wire?

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