JEE Mains · Physics · STD 11 - System of particles and rotational motion
- JEE Mains 2019
- Medium
- MCQ
A rod of length \(50\,cm\) is pivoted at one end. It is raised such that if makes an angle of \(30^o\) fro the horizontal as shown and released from rest. Its angular speed when it passes through the horizontal (in \(rad\,s^{-1}\) ) will be \((g = 10\,ms^{-2})\)

Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) \(\sqrt {30}\)
Step-by-step Solution
Detailed explanation
\(\begin{array}{l}
mg\frac{\ell }{2}\left( {\frac{1}{2}} \right) = \frac{1}{2}\left( {\frac{{m{\ell ^2}}}{3}} \right){\omega ^2}\\
\Rightarrow \,\,\,\omega = \sqrt {\frac{{3g}}{{2\ell }}} = \sqrt {30}
\end{array}\)
mg\frac{\ell }{2}\left( {\frac{1}{2}} \right) = \frac{1}{2}\left( {\frac{{m{\ell ^2}}}{3}} \right){\omega ^2}\\
\Rightarrow \,\,\,\omega = \sqrt {\frac{{3g}}{{2\ell }}} = \sqrt {30}
\end{array}\)
More questions from Physics
- In the given figure the magnetic flux through the loop increases according to the relation \(\phi_{B}(t)=10 t^{2}+20 t\), where \(\phi_{B}\) is in milliwebers and \(t\) is in seconds. The magnitude of current through \({R}=2 \,\Omega\) resistor at \({t}=5\, {s}\) is \(....\,{mA}\).
JEE Mains 2021 Medium - A circular loop of radius \(r\) is carrying current I A. The ratio of magnetic field at the centre of circular loop and at a distance \(r\) from the center of the loop on its axis is:JEE Mains 2023 Medium
- Consider a circular loop that is uniformly charged and has a radius \(\mathrm{a} \sqrt{2}\). Find the position along the positive z -axis of the cartesian coordinate system where the electric field is maximum if the ring was assumed to be placed in xy-plane at the origin :JEE Mains 2025 Easy
- In an electromagnetic wave the electric field vector and magnetic field vector are given as \(\vec{E}=E_{0} \hat{i}\) and \(\vec{B}=B_{0} \hat{k}\) respectively. The direction of propagation of electromagnetic wave is along.JEE Mains 2021 Medium
- Electromagnetic waves travel in a medium with speed of \(1.5 \times 10^8 \mathrm{~ms}^{-1}\). The relative permeability of the medium is \(2.0\) . The relative permittivity will be _______.JEE Mains 2024 Hard
- A certain gas is isothermally compressed to \(\left(\dfrac{1}{3}\right)^{rd}\) of its initial volume (\(V_o = 3\) litre) by applying required pressure. If the bulk modulus of the gas is \(3 \times 10^5\) N/m\(^2\), the magnitude of work done on the gas is _______ J.JEE Mains 2026 Hard
More PYQs from JEE Mains
- Two charges \(\mathrm{q}_1\) and \(\mathrm{q}_2\) are separated by a distance of 30 cm. A third charge \(q_3\) initially at ' C ' as shown in the figure, is moved along the circular path of radius 40 cm from C to D. If the difference in potential energy due to movement of \(q_3\) from \(C\) to \(D\) is given by \(\frac{\mathrm{q}_3 \mathrm{~K}}{4 \pi \epsilon_0}\), the value of K is :
JEE Mains 2025 Easy - If minimum possible work is done by a refrigerator in converting \(100\; grams\) of water at \(0^{\circ} C\) to ice, how much heat (in calories) is released to the surrounding at temperature \(27^{\circ} C\) (Latent heat of ice \(=80 Cal / gram\) ) to the nearest integer?JEE Mains 2020 Medium
- A particle of mass \(1\, {kg}\) is hanging from a spring of force constant \(100\, {Nm}^{-1 .}\) The mass is pulled slightly downward and released so that it executes free simple harmonic motion with time period \({T}\). The time when the kinetic energy and potential energy of the system will become equal, is \(\frac{{T}}{{x}}\). The value of \({x}\) is ..... .JEE Mains 2021 Hard
- The radii of two planets \(A\) and \(B\) are \(R\) and \(4 R\) and their densities are \(\rho\) and \(\rho / 3\) respectively. The ratio of acceleration due to gravity at their surfaces \(\left(g_A: g_B\right)\) will beJEE Mains 2023 Medium
- Match List\(-I\) with List\(-II\)
Choose the correct answer from the options given belowList\(-I\) List\(-II\) \((a)\) Isothermal \((i)\) Pressure constant \((b)\) Isochoric \((ii)\) Temperature constant \((c)\) Adiabatic \((iii)\) Volume constant \((d)\) Isobaric \((iv)\) Heat content is constant JEE Mains 2021 Medium - Time taken by light to travel in two different materials \(A\) and \(B\) of refractive indices \(\mu_{A}\) and \(\mu_{B}\) of same thickness is \(t_{1}\) and \(t_{2}\) respectively. If \(t_{2}-t_{1}=5 \times 10^{-10}\) s and the ratio of \(\mu_{A}\) to \(\mu_{B}\) is \(1: 2\). Then the thickness of material, in meter is: (Given \(v_{A}\) and \(v_{B}\) are velocities of light in \(A\) and \(B\) materials respectively).JEE Mains 2022 Hard