A 10 kg stone is suspended with a rope of breaking strength 30 kg-wt. The minimum time in which the stone can be raised through a height 10 m starting from rest is (Take, `g = 10 N kg^(-1)`).

Options

A. 0.5 s
B. 1s
C. `sqrt((2)/(3))`
D. 2s

Answer

B

Explanation

Tension in the string.
`T - mg = 30 xx10 = 300N`

`T - Mg = Ma`
From the figure ` 300 - 10 xx 10 = 10a`
`a= 20 ms^(-2)`
Thus the maximum acceleration with which the stone can be raised is `20 m s^(-2)` .
Given ` s = 10 m`
and u = 0
`therefore " " 10 = (1)/(2)(20)t^(2) rArr t = 1s`