Rotational Motion (NEET (National Eligibility cum Medical Entrance Test) Physics): Questions 94  98 of 125
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Question number: 94
» Rotational Motion » Rotational Kinetic Energy
Question
Two disc, each having moment of inertia 5 kg m ^{2} about its central axis, rotating with speeds 10 rad s ^{1} and 20 rad s ^{1}, are brought in contact face with their axes of the rotation coincided. The loss of kinetic energy in the process is,
Choices
Choice (4)  Response  

a.  125 J 

b.  5 J 

c.  0 J 

d.  2 J 

Question number: 95
» Rotational Motion » Torque
Question
A flywheel of mass 25 kg has a radius of 0.3 m. What force should be applied tangentially to the rim of the flywheel so that it acquires an angular acceleration of 4 rad s ^{2}?
Choices
Choice (4)  Response  

a.  6.8 N 

b.  11.2 N 

c.  7.5 N 

d.  2.6 N 

Question number: 96
» Rotational Motion » Moment of Inertia
Assertion (Ꭺ)
If two different axes are at same distance from the centre of mass of a rigid body, then moment of inertia of the given rigid body about both the axes will always be the same.
Reason (Ꭱ)
From parallel axis theorem, where all terms have usual meaning.
Choices
Choice (4)  Response  

a.  Ꭺ is true but Ꭱ is false 

b.  Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ 

c.  Ꭺ is false but Ꭱ is true 

d.  Both Ꭺ and Ꭱ are false 

Question number: 97
» Rotational Motion » Torque
Question
The torque required to stop a wheel of moment of inertia from a speed of 40 rad s ^{1} in 10 s is,
Choices
Choice (4)  Response  

a.  8 ⨯ 10 ^{3} Nm 

b.  8 Nm 

c.  0.8 Nm 

d.  0.08 Nm 

Question number: 98
» Rotational Motion » Concepts of Rotational Motion
Question
A solid sphere is rolling on a frictionless surface shown in figure with a transnational velocity v m/s. If sphere climbs up to height h then value of v should be
Choices
Choice (4)  Response  

a. 


b.  2gh 

c. 


d. 

