| ⇦ | 
| ⇨ |
A disc of moment of inertia (9.8/π²) kg m² is rotating at 600 rpm. If the frequency of rotation changes from 600 rpm to 300 rpm then what is the work done?
Options
(a) 1470 J
(b) 1452 J
(c) 1567 J
(d) 1632 J
Correct Answer:
1470 J
Explanation:
Given: Moment of inertia I = (9.8/π²) kgm²
ʋ₁ = 600 rpm = 10 rps; ʋ₂ = 300 rpm = 5 rps
.·. ω₁ = 2π ʋ₁ = 20π rad s⁻¹
.·. ω₂ = 2π ʋ₂ = 10π rad s⁻¹
Kinetic energy of rotation= (1/2) Iω²
Work done W = change in rotational kinetic energy
.·. work done W = (1/2).I [ω₂² – ω₂²]
W = (1/2) x (9.8/π²).[(10π)² – (20π)²]
= (1/2) x (9.8/π²).[-300 π²] = -1470 J
-ve sign show that rotational kinetic energy decreases.
Related Questions: - Which of the following will be σ if Y=2.4 η?
- In adiabatic expansion, product of PV
- A radio isotope X with a half life 1.4 x 10⁹ years decays to Y which is stable
- A coil of N turns and mean cross-sectional area A is rotating with uniform angular
- When ₉₀Th²²⁸ transforms to ₈₃Bi²¹², the number of emitted α and β particles
Topics: Motion of system of Particles and Rigid Body
(73)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- Which of the following will be σ if Y=2.4 η?
- In adiabatic expansion, product of PV
- A radio isotope X with a half life 1.4 x 10⁹ years decays to Y which is stable
- A coil of N turns and mean cross-sectional area A is rotating with uniform angular
- When ₉₀Th²²⁸ transforms to ₈₃Bi²¹², the number of emitted α and β particles
Topics: Motion of system of Particles and Rigid Body (73)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
18000+ students are using NEETLab to improve their score. What about you?
Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.
Share this page with your friends
Leave a Reply