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QNEET-2019-Ph-820: NEET 2019 Physics - Class 11 NEET-2019-Ph-820 Solution: A disc of radius 2 m and mass 100 kg rolls on a horizontal…
A disc of radius 2 m and mass 100 kg rolls on a horizontal floor. Its centre of mass has speed of 20 cm/s. How much work is needed to stop it? 1 J 2 J 3 J 30 kJ
Multiple Choice Options
- A 1 J
- B 2 J
- C 3 J
- D 30 kJ
Step-by-Step Verified Solution
_ = V R = 0.2 2 = 0.1 rad/sec
Apply the law of conservation of energy,
Work required = change in kinetic energy
Since, final KE = 0
And, initial KE = 1 2 m v 2 + 1 2 I _ 2
= 1 2 m v 2 + 1 2 M l 2 2 _ 2
= 1 2 ( 100 ) ( 0.2 ) 2 + 1 2 100 _ ( 2 ) 2 2 ( 0.1 ) 2
= 1 + 1 2 _ 4 = 3 J