A mass of 1 kg is suspended by means of a thread. The system is (i) lifted up with an acceleration of `4.9ms^(-2)` (ii) lowered with an acceleration of `4.9ms^(-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)`
Case - II:

Using newton.s second law of motion:
`mg -T_(2) = ma`
`T_(2) = m(g-a)`
From equation (i) and (ii)
`T_(1)/T_(2) = (g+a)/(g-a) = (9.8 + 4.9)/(9.8-4.9) = 3/1`