WBJEE · Physics · Laws of Motion

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

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

Verified Solution

Answer & Solution

Correct Answer

(A) 3: 1

Step-by-step Solution

Detailed explanation

When the body of mass m lifted up the forces acting on the body \[ \begin{aligned} T_{1}-m g &=\frac{m g}{2} \\ T_{1} &=m g+\frac{m g}{2}=\frac{3 m g}{2} \end{aligned} \] (ii) When the body lowered the acting forces \[ \left(m g-T_{2}\right)=\frac{m g}{2} \]…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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

Step-by-step Solution

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