CBSE Class 11 (Science) Rotational Motion — practice questions
91 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice CBSE Class 11 (Science) Rotational Motion in the app →A body with a perfectly definite and unchanging shape is called:In a rigid body, the distances between pairs of particles:Is any real body truly rigid?Fixing a body along a straight line leaves only which motion?The fixed line about which a body rotates is its:The rotational counterpart of force is the moment of force, also called:Torque is which kind of quantity?The SI unit of the moment of force is the:If the directions of both r and F are reversed, the torque direction:The rotational analogue of mass is the:The SI unit of moment of inertia is:Moment of inertia is written as M times which square?Moment of inertia measures a body's rotational:Which machine is named as using this property practically?Conservation of angular momentum means conservation of how many components?Conservation of angular momentum is the rotational analogue of conserving:For rotational equilibrium, the sum of the torque components must be:In a rotating rigid body, each particle moves in:A ring of mass 2 kg, radius 0.5 m, spins about its central perpendicular axis. Its I isA uniform disc of mass 4 kg and radius 0.2 m turns about its central axis normal to its face. Find its moment A rod of mass 3 kg, length 2 m, spins about a perpendicular axis at its midpoint. Its I isA disc of mass 8 kg and radius 0.5 m is turned about one of its diameters. What is its moment of inertia?For a thin ring, what is the ratio of I about a diameter to I about its central perpendicular axis?A hollow and a solid cylinder share the same mass and radius. Ratio of I (hollow : solid) about their axes?What is the radius of gyration of a uniform disc of radius R about its diameter?A thin rod of length L spins about a perpendicular axis through its centre. Its radius of gyration isA body of mass 2 kg has moment of inertia 8 kg m^2 about an axis. What is its radius of gyration?Which quantity is the rotational analogue of mass in linear motion?The rotational analogue of force in linear motion is calledWhich statement about the moment of inertia of a rigid body is true?Torque has the same dimensions as which quantity?Torque and work share dimensions. How do they differ?A 10 N force acts at right angles to a spanner, 0.5 m from the bolt. What torque does it produce?A 10 N force acts 0.5 m from a pivot at 30 degrees to the position vector. Find the torque.When is the torque of a non-zero force about a point zero?If both the position vector r and force F are reversed, the torque r x FWhere must a force be applied on a door to open it most effectively?Vectors of size 3 and 4 are 30 degrees apart. Magnitude of their cross product?What is the cross product of a vector with itself, a x a?For the unit vectors of a right handed system, what is i x j?Under reflection (x to -x, y to -y, z to -z), the cross product a x bWhile applying the right hand rule to a x b, through which angle is the rotation taken?A wheel spins at 10 rad/s. What is the speed of a point 0.3 m from the axis?Pure rotation of a rigid body means all its parts have the sameFor rotation about a fixed axis, the angular velocity vector liesThe linear velocity of a particle of a rotating rigid body is given byRotation of a rigid body about a fixed axis needs how many independent variables?A wheel starts from rest with angular acceleration 2 rad/s^2. What is its angular speed after 5 s?A disc starts from rest and speeds up at 2 rad/s^2. Through what angle does it turn in 5 s?A rotor at 4 rad/s gains speed uniformly at 2 rad/s^2 over 5 rad. Its final angular speed isA motor wheel goes from 1200 rpm to 3120 rpm uniformly in 16 s. What is its angular acceleration?A wheel turns at 1200 revolutions per minute. Its angular speed in rad/s isA net torque of 20 N m acts on a body with I = 4 kg m^2. Its angular acceleration isA flywheel with I = 2 kg m^2 spins at 4 rad/s. What is its rotational kinetic energy?A body with I = 2 kg m^2 rotates at 3 rad/s about a symmetry axis. Its angular momentum isA shaft carries a torque of 10 N m while turning at 5 rad/s. What power does it deliver?A constant torque of 5 N m turns a wheel through 4 rad. How much work is done?For a fixed axis, angular acceleration of a rigid body isIn fixed axis rotation, which forces can be left out of the torque sum?Work done by external torques on a perfectly rigid body goes intoThe rate of change of angular momentum of a particle equals theAngular momentum of a particle about O is zero if its momentum lineA 2 kg particle moves at 3 m/s along a line 4 m from point O. Its angular momentum about O isA free particle moves in a straight line at constant velocity. Its angular momentum about a fixed pointTotal angular momentum of a system is conserved when the total externalInternal torques cancel if forces obey Newton's third law and also actA turntable with I = 4 kg m^2 spins at 3 rad/s. With no external torque, I falls to 2 kg m^2. New ω?You spin on a free swivel chair and stretch out your arms. Result?A diver curls into a tuck in mid air. Why does the diver spin faster?A skater pulls in her arms while spinning freely. Her rotational kinetic energyWhich everyday action applies a couple?Why does a compass needle turn in the Earth's magnetic field without moving off?Two opposite 5 N forces form a couple with lines of action 0.4 m apart. The couple's moment isHow many independent conditions must hold for general mechanical equilibrium of a rigid body?If all forces on a rigid body are coplanar, equilibrium needs how many conditions?For a particle, rather than an extended body, equilibrium only requires thatA lever lifts a 200 N load with a 0.5 m load arm. The effort arm is 2 m. What effort is needed?A lever has effort arm 2 m and load arm 0.5 m. What is its mechanical advantage?A lever has mechanical advantage greater than one whenOn a lever, the point about which it pivots is called theThe centre of gravity of a body coincides with its centre of mass whenHow is the CG of an irregular sheet found by hanging it?The position of the centre of mass of a body depends onA rigid body fixed at one point or along a line can haveThe total torque on a system does not depend on the chosen origin when the total externalTwo small masses m are fixed at the ends of a light rod of length l. I about a perpendicular axis through its Moment of inertia about an axis equals the ratio of the applied torque to the resultingThe moment of inertia of a composite rigid system about an axis isA wheel turns through angle Δθ in time Δt. Its average angular velocity isMoment of force and angular momentum are both defined asWhich property is shared by both the scalar and the vector product?