The student has a mass of 84.0 kg, and the height of the water slide is 11.5 m.

Question

The student has a mass of 84.0 kg, and the height of the water slide is 11.5 m. The kinetic frictional force does -6.90 103 J of work on the student.


(d) Based on the work-energy theorem, what is the algebraic expression for the speed vf of the student at the bottom of the slide? Express your answer in terms of the work Wnc done by the nonconservative kinetic frictional force, the mass m, the initial speed v0 of the student, and the initial and final heights, h0 and hf, of the slide. (Answer using W_n to be the work done by the nonconservative kinetic frictional force, m to be the mass of the student, v_0 to be the initial speed, h_0 to be the initial height, h_f to be the final height, and g to be the acceleration due to gravity).
vB =


(e) How fast is the student going at the bottom of the slide if she starts from rest at the top?
Number Unit
vf =

Explanation / Answer

By energy conservation (accounting for nonconservative forces),

mgh = (1/2)mv2 + WNC

==> v = (2(gh - WNC / m)) = (2((9.8 m/s2)(11.5 m) - (6.90 x 103) / (84.0 kg))) = 7.82 m/s

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