Answer to Question #128494 in Mechanics | Relativity for Osandi

Question

7. An 80.0 kg student running at 3.5 m/s grabs onto a rope that it hanging vertically.
a. How much kinetic energy does the student have prior to grabbing the rope?
b. How high will the student swing?

Answer 1

a. $E_k={{mv^2}\over2}={{80\sdot{3.5^2}}\over2}=490$ J

b. $E_k=E_p\implies$ ${{mv^2}\over2}=mgh\implies$ $h={{v^2}\over2g}={{{3.5^2}}\over2\sdot9.81}=0.624$ m = 62.4 cm