A 75-kg person, starting from rest, sleds down a slide 40. m high hill reaching the bottom with a speed of 18 m/s. Calculate a) the PE at the top,

b) the KE at the bottom of the hill,

c) and finally, the thermal energy that was generated in the process.

Which changes of state do the labels represent? a: b: c:

The heliocentric and the geocentric models of the solar system included these central principles

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