Laws of Motion

JEE Main level, numerical answer, medium

76 of 210

Question 76 of 210



A string of length
LL is fixed at one end and carries a mass of MM at the other end. The mass makes (3π)\left(\frac{3}{\pi}\right) rotations per second about the vertical axis passing through end of the string as shown. The tension in the string is ……\ldots\ldots ML.

Show answer and solution

Answer: 36

ω=3π×2π=6rad/sR=Lsin⁡θ\begin{aligned} & \omega=\frac{3}{\pi} \times 2 \pi=6 \mathrm{rad} / \mathrm{s} \\ & R=L \sin \theta\end{aligned}


and
T=Mg2+ω4R2T=M \sqrt{g^2+\omega^4 R^2}
Also,
Tsin⁡θ=Mω2⋅Lsin⁡θT \sin \theta=M \omega^2 \cdot L \sin \theta
$\begin{aligned}

& \Rightarrow \quad T=M(36) \mathrm{L} \\

& \Rightarrow \quad T=36 \mathrm{ML}

\end{aligned}$

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.
See it move: Laws of motion, friction and pulleys simulationDrag the sliders and watch the numbers in this question change.

More Physics practice

JEE Main Physics practice question on Laws of Motion (Equilibrium of Forces), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.