Rotational Motion — Previous-Year Questions

Q1. A wheel spinning at 100 rpm. Angular velocity in rad/s:

Q2. A flywheel starting from rest reaches 20 rad/s in 5 s. Angular acceleration:

Q3. A point at r = 0.5 m on a disc rotating at ω = 10 rad/s has linear speed:

Q4. Centripetal acceleration of a point at r = 0.2 m rotating at ω = 5 rad/s:

Q5. All points of a rotating rigid body share the same:

Q1. Moment of inertia of a uniform rod of mass M and length L about its center:

Q2. I of a thin ring of mass M and radius R about its central axis:

Q3. I of a solid sphere of mass M and radius R about diameter:

Q4. Why is a thin ring's I larger than a solid disk's (same M and R)?

Q5. Newton's 2nd law for rotation:

Q1. A 10 N force is applied perpendicular to a 0.5 m wrench. Torque:

Q2. Torque is zero when:

Q3. For static equilibrium, the conditions are:

Q4. Two parallel forces 5 N each in OPPOSITE directions, 0.4 m apart. Net torque (couple):

Q5. Why are door handles placed FAR from hinges?

Q1. I of a uniform rod about its end (length L, mass M):

Q2. I of a disk of mass M, radius R about a tangent in the plane:

Q3. Parallel-axis theorem applies:

Q4. Perpendicular-axis theorem applies to:

Q5. I_CM of a body is always:

Q1. I = 2 kg·m², ω = 10 rad/s. K_rot:

Q2. Total KE of a solid sphere (mass M, speed v) rolling without slipping:

Q3. If a flywheel has I = 50 kg·m² and ω = 100 rad/s, energy stored:

Q4. Power transferred to a rotor by torque 20 N·m at ω = 5 rad/s:

Q5. If a rolling sphere and a sliding block both start from rest at top of an incline (same height), at the bottom:

Q1. An ice skater with arms out (I = 5 kg·m², ω = 2 rad/s) pulls them in (I = 2 kg·m²). New ω:

Q2. KE of the skater after pulling arms in changes by factor:

Q3. Earth's day length is slowly INCREASING because:

Q4. Conservation of L requires:

Q5. A pulsar (collapsed star) has ω ~ 600 rad/s. The original star had ω ~ 10⁻⁶ rad/s. Ratio of R_old to R_new (assuming uniform sphere):

Q1. A solid sphere rolls down an incline of angle 30°. Its acceleration (g = 10):

Q2. Which rolls down an incline FASTEST (same h)?

Q3. In pure rolling, the velocity of the contact point with the ground is:

Q4. KE of a rolling solid sphere of speed v: translational and rotational parts ratio:

Q5. Static friction in pure rolling motion: