TS EAMCET · Physics · Rotational Motion
A thin uniform circular disc of mass \(\frac{10}{\pi^2} \mathrm{~kg}\) and radius 2 m is rotating about an axis passing through its centre and perpendicular to its plane. The work done to increase the angular speed of the disc from \(90 \mathrm{rev} / \mathrm{min}\) to \(120 \mathrm{rev} / \mathrm{min}\) is
- A 35 J
- B 70 J
- C 140 J
- D 210 J
Answer & Solution
Correct Answer
(B) 70 J
Step-by-step Solution
Detailed explanation
\(I = \frac{1}{2} M R^2 = \frac{1}{2} \left(\frac{10}{\pi^2}\right) (2)^2 = \frac{20}{\pi^2} \mathrm{~kg \cdot m^2}\) \(\omega_i = 90 \times \frac{2\pi}{60} = 3\pi \mathrm{~rad/s}\) \(\omega_f = 120 \times \frac{2\pi}{60} = 4\pi \mathrm{~rad/s}\)…
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
- The work done to accelerate an electron from rest so that it can have a de Broglie wavelength of \(6600 Å\) is nearly
(Planck's constant \(=6.6 \times 10^{-34} \mathrm{Js}\) and mass of electron \(=9 \times 10^{-31} \mathrm{~kg}\) )TS EAMCET 2025 Medium - A particle of mass collides with a particle of at rest. After the elastic collision, the two particles moves at an angle of with respect to each other. The ratio isTS EAMCET 2020 Hard
- Two particles execute simple harmonic motion (SHM) along close parallel lines. SHM of the both the particles have same frequency and same amplitude. When they pass each other moving in opposite direction each time, their displacement is half their amplitude. Then, their phase difference isTS EAMCET 2021 Hard
- The position vector of a particle moving in a plane is given by \(\mathbf{r}=a \cos \omega t \hat{\mathbf{i}}+b \sin \omega t \hat{\mathbf{j}}\), where \(\hat{\mathbf{i}}\) and \(\hat{\mathbf{j}}\) are the unit vectors along the rectangular axes \(X\) and \(Y ; a, b\) and \(\omega\) are constants and \(t\) is time. The acceleration of the particle is directed along the vectorTS EAMCET 2018 Easy
- A stiff spring having spring constant \(k=400 \mathrm{~N} / \mathrm{m}\) is attached to the floor vertically. A mass \(m=10 \mathrm{~kg}\) is placed on top of the spring. The block oscillates if it is pressed downward and released. Find the extension in the spring at which the block loses contact with spring. (Take, \(g=10 \mathrm{~m} / \mathrm{s}^2\) )
TS EAMCET 2020 Medium - The base current in a transistor circuit changes from \(45 \mu \mathrm{A}\) to \(140 \mu \mathrm{A}\). Accordingly, the collector current changes from \(0.2 \mathrm{~mA}\) to \(0.400 \mathrm{~mA}\). The gain in current isTS EAMCET 2013 Easy
More PYQs from TS EAMCET
- A pipe having an internal diameter \(D\) is connected to another pipe of same size. Water flows into the second pipe through ' \(n\) ' holes, each of diameter \(d\). If the water in the first pipe has speed \(v\), the specd of water leaving the second pipe isTS EAMCET 2012 Hard
- A typical integrated circuit (IC) consisting of logic gates is termed asTS EAMCET 2021 Easy
- A piece of metal has a weight of \(49 \mathrm{gm}\) in air and \(39 \mathrm{gm}\) in a liquid of density \(1.2 \times 10^3 \mathrm{~kg} / \mathrm{m}^3 \mathrm{kept}\) at \(32^{\circ} \mathrm{C}\). When the temperature of the liquid is raised to \(45^{\circ} \mathrm{C}\) the metal piece has a weight of \(40 \mathrm{gm}\). If the density of the liquid at \(42{ }^{\circ} \mathrm{C}\) is \(1.0 \times 10^3 \mathrm{~kg} / \mathrm{m}^3\), then the coefficient of linear expansion of the metal isTS EAMCET 2022 Medium
- The amplitude of a damped oscillator varies with time as \(\mathrm{A}(\mathrm{t})=\mathrm{A}_{\mathrm{o}} \exp (-\mathrm{bt} / 2 \mathrm{~m})\) where \(\mathrm{b}=70 \mathrm{~g} / \mathrm{s}\) and \(\mathrm{m}=200 \mathrm{~g}\). How long does it take for the mechanical energy to drop to one - fourth of its initial value? \([\) Take \(\ln 2=0.7]\)TS EAMCET 2022 Medium
- A semi-circular loop of radius \(30 \mathrm{~cm}\) wire carries current \(6 \mathrm{~A}\). An uniform magnetic field \(0.5 \mathrm{~T}\) is present perpendicular to the plane of the loop. What is the magnitude of force exerted on the wire?TS EAMCET 2019 Easy
- A force of \(6.4 \mathrm{~N}\) stretches a vertical spring by \(0.1 \mathrm{~m}\). If it were to oscillate with a period of \(\frac{\pi}{4}\) then the mass that is to be suspended from the spring isTS EAMCET 2023 Easy