JEE Mains · Physics · STD 11 - System of particles and rotational motion
- JEE Mains 2021
- Hard
- MCQ
A triangular plate is shown. A force \(\overrightarrow{ F }=4 \hat{ i }-3 \hat{ j }\) is applied at point \(P\). The torque at point \(P\) with respect to point \('O'\) and \('Q'\) are
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Answer & Solution
Correct Answer
(A) \(-15-20 \sqrt{3}, 15-20 \sqrt{3}\)
Step-by-step Solution
Detailed explanation
\(\overrightarrow{ F }=4 \hat{ i }-3 \hat{ j }\)
\(\overrightarrow{ r }_{1}=5 \hat{ i }+5 \sqrt{3} \hat{ j } \& \overrightarrow{ r }_{2}=-5 \hat{ i }+5 \sqrt{3} \hat{j}\)
Torque about \('O'\)
\(\vec{\tau}_{0}=\overrightarrow{ r }_{1} \times \overrightarrow{ F }=(-15-20 \sqrt{3}) \hat{ k }=(15+20 \sqrt{3})(-\hat{ k })\)
Torque about \('Q'\)
\(\vec{\tau}_{Q}=\overrightarrow{ r }_{2} \times \overrightarrow{ F }=(-15+20 \sqrt{3}) \hat{ k }=(15-20 \sqrt{3})(-\hat{ k })\)
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