A 8.0 kg box is released from rest on a frictionless ramp. The box slides from the ramp onto a rough
horizontal surface with a friction mk -0.50. The starts at
a height of 4 meters (yo = 4 m).
What is the formula for force friction?
What is the formula for work (W)?
What type of energy does the box have at the begging on this problem?
Where does the energy go after the box come to rest?
What distance d will the box slide?

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