COMEDK · Physics · 8. Rotational Motion

A wheel is free to rotate about a horizontal axis through O. A force of \(200 \mathrm{~N}\) is applied at a point \(\mathrm{P} 2 \mathrm{~cm}\) from the center \(\mathrm{O}\). OP makes an angle of \(55^{\circ}\) with \(\mathrm{x}\) axis and the force is in the plane of the wheel making an angle of \(25^{\circ}\) with the horizontal axis. What is the torque?

A 3.2 N m
B 2 N m
C 4 N m
D 3.4 N m

Verified Solution

Answer & Solution

Correct Answer

(B) 2 N m

Step-by-step Solution

Detailed explanation

The torque \(\vec{\tau}\) is defined as \(\vec{\tau} = \vec{r} \times \vec{F}\), where \(\vec{r}\) is the position vector of the point of application P relative to the axis O, and \(\vec{F}\) is the applied force. The magnitude of the torque is given by…

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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