Question

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)`).
A. 0.5 s
B. 1.0 s
C. `sqrt((2)/(3))s`
D. 2.0 s

Answer 1

Correct Answer - B
Tension in the string T = mg
`= 30 xx10=300 N`
`T - Mg=Ma`
From the figure, `300 - 10 xx 10 =10a`
`therefore" "a = 20 ms^(-2)`
Thus, the maximum acceleration with which the stone can be raised is `20 ms^(-2)`
Given, s = 10 m and u = 0
`therefore" "10=(1)/(2)(20)t^(2)`
`implies " "t = 1s`