At a metro station, a girl walks up a stationary escalator in time `t_1` If she remains stationary on the escalator, then the escalator take her up in time `t_2`. The time taken by her to walk up the moving escalator will be.

Options

A. `(t_(1)+t_(2))//2`
B. `t_(1)t_(2)//(t_(2)-t_(1))`
C. `t_(1)t_(2)//(t_(2)+t_(1))`
D. `t_(1)-t_(2)`

Answer

C

Explanation

velocity of girl `v_(g)=(L)/(t_(1))`
Velocity of escalator `v_(e)=(L)/(t_(2))`
Net velocity of the girl`=v_(g)+v_(e)=(L)/(t_(1))+(L)/(t_(2))`
`(L)/(t)+(L)/(t_(1))+(L)/(t_(2))impliest=(t_(1)t_(2))/(t_(1)+t_(2))`