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NEET
Exam
NEET
Subject
Physics
Chapter
Rotational Motion

NEET · Physics · Rotational Motion

Match the following columns (R= radius, k= Radius of gyration ) (...

Match the following columns (R=(\mathrm{R}= radius, k=\mathrm{k}= Radius of gyration )) (

Column IColumn II

(A)
<br>′k′forasolidsphererotating</td></tr><tr><td><br>aboutitstangent<br>\begin{array}{l}<br> ' k ' for a solid sphere rotating</td></tr><tr><td><br> about its tangent <br>\end{array}(P)\sqrt{2} R

(B)
<br>′k′foraringrotatingaboutits</td></tr><tr><td><br>tangentperpendiculartoitsplane<br>\begin{array}{l}<br> ' k ' for a ring rotating about its</td></tr><tr><td><br> tangent perpendicular to its plane <br>\end{array}(Q)\frac{R}{2}

(C)
<br>′k′forauniformsolidright</td></tr><tr><td><br>circularconerotatingaboutits</td></tr><tr><td><br>centralaxis<br>\begin{array}{l}<br> ' k ' for a uniform solid right</td></tr><tr><td><br> circular cone rotating about its</td></tr><tr><td><br> central axis <br>\end{array}(R)\frac{\sqrt{7}}{\sqrt{5}} R

(D)
<br>′k′forauniformdiscrotation</td></tr><tr><td><br>aboutitsdiameter<br>\begin{array}{l}<br> ' k ' for a uniform disc rotation</td></tr><tr><td><br> about its diameter <br>\end{array}(S)\frac{\sqrt{3}}{\sqrt{10}} R


)

Options

  1. A(A)−(p);(B)−(R);(C)−(Q);(D)−(s)(\mathrm{A})-(\mathrm{p}) ;(\mathrm{B})-(\mathrm{R}) ;(\mathrm{C})-(\mathrm{Q}) ;(\mathrm{D})-(\mathrm{s})
  2. B(A)−(p);(B)−(Q);(C)−(s);(D)−(P)(\mathrm{A})-(\mathrm{p}) ;(\mathrm{B})-(\mathrm{Q}) ;(\mathrm{C})-(\mathrm{s}) ;(\mathrm{D})-(\mathrm{P})
  3. C(A)−(Q);(B)−(R);(C)−(p);(D)−(S)(\mathrm{A})-(\mathrm{Q}) ;(\mathrm{B})-(\mathrm{R}) ;(\mathrm{C})-(\mathrm{p}) ;(\mathrm{D})-(\mathrm{S})
  4. D(A)−(R);(B)−(P);(C)−(S);(D)−(Q)(\mathrm{A})-(\mathrm{R}) ;(\mathrm{B})-(\mathrm{P}) ;(\mathrm{C})-(\mathrm{S}) ;(\mathrm{D})-(\mathrm{Q})

Correct answer

D. (A)−(R);(B)−(P);(C)−(S);(D)−(Q)(\mathrm{A})-(\mathrm{R}) ;(\mathrm{B})-(\mathrm{P}) ;(\mathrm{C})-(\mathrm{S}) ;(\mathrm{D})-(\mathrm{Q})

Step-by-step solution

Relationship between radius of gyration and the moment of inertia about an axis is as follows: I=mk2\mathrm{I}=\mathrm{mk}^2 Summary for the different cases is listed below: (

Case</td><td>Momentofinertia</td><td>Moment of inertia
<br>Radiusof</td></tr><tr><td><br>gyration<br>\begin{array}{l}<br> Radius of</td></tr><tr><td><br> gyration <br>\end{array}

<br>Solidsphererotating</td></tr><tr><td><br>aboutitstangent<br>\begin{array}{l}<br> Solid sphere rotating</td></tr><tr><td><br> about its tangent <br>\end{array}
<br>I=25mR2+mR2</td></tr><tr><td><br>Usingparallelaxistheorem.<br>\begin{array}{l}<br>I=\frac{2}{5} mR^2+mR^2</td></tr><tr><td><br> Using parallel axis theorem. <br>\end{array}\frac{\sqrt{7}}{\sqrt{5}} R

<br>Ringrotatingaboutits</td></tr><tr><td><br>tangentperpendicularto</td></tr><tr><td><br>itsplane<br>\begin{array}{l}<br> Ring rotating about its</td></tr><tr><td><br> tangent perpendicular to</td></tr><tr><td><br> its plane <br>\end{array}
<br>I=mR2+mR2</td></tr><tr><td><br>Usingparallelaxistheorem.<br>\begin{array}{l}<br>I=mR^2+mR^2</td></tr><tr><td><br> Using parallel axis theorem. <br>\end{array}\sqrt{2} R

<br>Uniformsolidright</td></tr><tr><td><br>circularconerotating</td></tr><tr><td><br>aboutitscentralaxis<br>\begin{array}{l}<br> Uniform solid right</td></tr><tr><td><br> circular cone rotating</td></tr><tr><td><br> about its central axis <br>\end{array}
<br>I=310mR2</td></tr><tr><td><br>Usingmomentofinertiaofa</td></tr><tr><td><br>discandintegratingittoobtain</td></tr><tr><td><br>thecone.<br>\begin{array}{l}<br>I=\frac{3}{10} mR^2</td></tr><tr><td><br> Using moment of inertia of a</td></tr><tr><td><br> disc and integrating it to obtain</td></tr><tr><td><br> the cone. <br>\end{array}\frac{\sqrt{3}}{\sqrt{10}} R

<br>Uniformdiscrotation</td></tr><tr><td><br>aboutitsdiameter<br>\begin{array}{l}<br> Uniform disc rotation</td></tr><tr><td><br> about its diameter <br>\end{array}
<br>I=12(mR22)</td></tr><tr><td><br>Usingperpendicularaxis</td></tr><tr><td><br>theorem<br>\begin{array}{l}<br>I=\frac{1}{2}\left(\frac{mR^2}{2}\right)</td></tr><tr><td><br> Using perpendicular axis</td></tr><tr><td><br> theorem <br>\end{array}\frac{R}{2}


)
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