JEE Mains · Physics · STD 11 - 6. system of particles and rotational motion
A uniform disc of radius \(R\) and mass \(M\) is free to rotate only about its axis. A string is wrapped over its rim and a body of mass \(m\) is tied to the free end of the string as shown in the figure. The body is released from rest. Then the acceleration of the body is
- A \(\frac{{2mg}}{{2m + M}}\)
- B \(\frac{{2Mg}}{{2m + M}}\)
- C \(\frac{{2mg}}{{2M + m}}\)
- D \(\frac{{2Mg}}{{2M + m}}\)
Answer & Solution
Correct Answer
(A) \(\frac{{2mg}}{{2m + M}}\)
Step-by-step Solution
Detailed explanation
From the codition of equilibrium \(mg - T = ma \) \(....(i)\) \(RT =\) \(I\alpha \) \(\begin{array}{l} \overline a = \overline \alpha \times R\,and\,I = \frac{{M{R^2}}}{2}\\ \,\,\,\,\,\,\,\,\,\,\,RT = \frac{{M{R^2}}}{2}.\frac{a}{R} \end{array}\) Tension in string,…
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- An electron, a proton and an alpha particle having the same kinetic energy are moving in circular orbits of radii \(r_e,r_p\) and \({r_\alpha }\) respectively in a uniform magnetic field \(B\). The relation between \(r_e,r_p\) and \(\;{r_\alpha }\) isJEE Mains 2018 Medium
- A point like object is placed at a distance of \(1\, m\) in front of a convex lens of focal length \(0.5\, m .\) A plane mirror is placed at a distance of \(2\,m\) behind the lens. The position and nature of the final image formed by the system isJEE Mains 2020 Medium
- The resistance of a conductor at \(15^{\circ} {C}\) is \(16\, \Omega\) and at \(100\, {C}\) is \(20\, \Omega\). What will be the temperature coefficient of resistance of the conductor?JEE Mains 2021 Medium
- A string is wound around a hollow cylinder of mass \(5\, kg\) and radius \(0.5\,m\). If the string is now pulled with a horizontal force of \(40\, N\), and the cylinder is rolling without slipping on a horizontal surface (see figure), then the angular acceleration of the cylinder will be ......... \(rad/s^2\) .(Neglect the mass and thickness of the string)
JEE Mains 2019 Medium - The waves emitted when a metal target is bombarded with high energy electrons areJEE Mains 2023 Easy
- A moving coil galvanometer allows a full scale current of \(10^{-4}\, A\). A series resistance of \(2\, M\,\Omega \) is required to convert the above galvanometer into a voltmeter of range \(0 -5\, V\). Therefore the value of shunt resistance required to convert the above galvanometer into a ammeter of range \(0-10\, mA\) is....\(\Omega \)JEE Mains 2019 Medium
More PYQs from JEE Mains
- The term independent of ' \(x\) ' in the expansion of \(\left(\frac{x+1}{x^{2 / 3}-x^{1 / 3}+1}-\frac{x-1}{x-x^{1 / 2}}\right)^{10}\), where \(x \neq 0,1\) is equal to \(.....\)JEE Mains 2021 Hard
- If the eccentricity \(e\) of the hyperbola \(\dfrac{x^2}{a^2} - \dfrac{y^2}{b^2} = 1\), passing through \((6, 4\sqrt{3})\), satisfies \(15(e^2 + 1) = 34e\), then the length of the latus rectum of the hyperbola \(\dfrac{x^2}{b^2} - \dfrac{y^2}{2(a^2+1)} = 1\) is:JEE Mains 2026 Medium
- The sum of the series
\(2 \times 1 \times{ }^{20} \mathrm{C}_4-3 \times 2 \times{ }^{20} \mathrm{C}_5+4 \times 3 \times{ }^{20} \mathrm{C}_6-5 \times 4\) \(\times { }^{20} \mathrm{C}_7+\ldots+18 \times 17 \times{ }^{20} \mathrm{C}_{20}\), is equal toJEE Mains 2025 Medium - A part of a complete circuit is shown in the figure. At some instant, the value of current \(I\) is \(1\, A\) and it is decreasing at a rate of \(10^{2}\, A s ^{-1}\) The value of the potential difference \(V _{ P }- V _{ Q }\) (in volts) at that instant, is.
JEE Mains 2020 Medium - If \(\mathrm{G}\) be the gravitational constant and \(\mathrm{u}\) be the energy density then which of the following quantity have the dimension as that the \(\sqrt{\mathrm{uG}}\)?JEE Mains 2024 Hard
- Let the equation of the plane \(P\) containing the line \(x+10=\frac{8-y}{2}=z\) be \(a x+b y+3 z=2(a+b)\) and the distance of the plane \(P\) from the point \((1,27,7)\) be c. Then \(a^2+b^2+c^2\) is equal to \(.............\).JEE Mains 2023 Hard