A mass of 1 kg is suspended by means of a thread. The system is (i) lifted up with an acceleration of `4.9 ms^(-2)` (ii) lowered with an acceleration of 4.9 `ms^(- 2)`. The ratio of tension in the first and second case is

Options

A. `3:1`
B. `1:2`
C. `1:3`
D. `2:1`

Answer

A

Explanation

Case-I
Using Newton.s second law of motion, `T_(1)` - mg= ma
`T_(1)=m(g+a)` …(i)
Case-II
Using Newton.s second law of motion,
`mg-T_(2)=ma`
`T_(2)=m(g-a)` …(ii)
From eqn. (i) and (ii)
`(T_(1))/(T_(2))=(g+a)/(g-a)=(9.8+4.9)/(9.8-4.9)=3/1`