An athelete completes one round of a circular track of radius `R` in 40 seconds. What will be the displacement at the end of ` 2 min. 20 second ?

Options

A. zero
B. 2R
C. `2piR`
D. `7piR`

Answer

B

Explanation

t=2min 20 sec=120+20=140 sec.
after each complete rotation, displacement becomes zero.
Number of rotation `=(140)/(40)=3+(1)/(2)`
`therefore` displacement in `(1)/(2)` rotation=2R