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Units And Measurement

Question
CBSEENPH11017713

A spherical solid ball rolls on a table. What fraction of its total kinetic energy is rotational kinetic energy?

Solution

When a body rolls without slipping, it possesses both rotational kinetic energy and translational kinetic energy.
Total kinetic energy of solid ball is,
K.E = Kt + Kr
straight K. straight E space equals space 1 half space Iω squared space plus space 1 half mv squared space

space space space space space space space equals 1 half open parentheses 2 over 5 MR squared close parentheses straight omega squared space plus space 1 half mv squared

space space space space space space equals space 1 fifth MR squared space straight omega squared space plus space 1 half mv squared space

space space space space space space equals space 1 fifth mv squared space plus space 1 half mv squared space

straight K. straight E space equals space 7 over 10 space mv squared

That space is comma space

Rotational space straight K. straight E space equals space 1 fifth mv squared space
So comma space

Total space straight K. straight E space equals space 7 over 10 space mv squared space
Fractional space rotational space straight K. straight E space equals space bevelled fraction numerator begin display style 1 fifth end style mv squared over denominator 7 over 10 space mv squared space end fraction space
space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals space 2 over 7