Suppose an electron orbits a stationary proton at'a radius of 5.3 X 10" m. What speed must the electron
have if its mass times its centripetal acceleration is to be
equal to the electrostatic force of attraction between the
electron and the proton?

Awater slide of length l has a vertical drop of h. abby's mass is m. an average friction force of magnitude f opposes her motion. she starts down the slide at initial speed vi. use work-energy ideas to develop an expression for her speed at the bottom of the slide. then evaluate your result using unit analysis and limiting case analysis. express your answer in terms of the variables h, m, l, vi, f and appropriate constants. vf v f