An athlete in the Olympic gamed covers a distance of `100 m` in `10 s`. His kinetic energy can be estimated to be in range.
(1) `200 J - 500 J`
(2) `2 xx 10^(5) J - 3 xx 10^(5) J`
(3) `20,000 J - 50,000 J`
(4) `2,000 J - 5,000 J`.

Options

A. `200 J - 500 J`
B. `2 xx 10^(5) J - 3 xx 10^(5) J`
C. `20,000 J - 50,000 J`
D. `2,000 J - 5,000 J`.

Answer

D

Explanation

average velocity
`v_(av) = (s)/(l) = (100)/(10) = 10 m//s`
Assuming an athelete has mass about `50` to `100 kg` or average mass `75 kg`,
His average kinetic energy.
`k_(av) = (1)/(2) mv_(av)^(2) = (1)/(2) xx 75 xx 100 = 3750 J`
Minimum possible kinetic energy, `(for 50 kg)`
`k_(min) = (1)/(2) mv_(av)^(2) = (1)/(2) xx 50 xx 100 = 2500 J`
Maximum possible kinetic energy `(for 100 kg)`
`k_(max) = (1)/(2) mv_(av)^(2) = (1)/(2) xx100xx100 = 5000 J`
Hence the kinetic energy could be in the range `2000` to `5000 J`.