Home › NEET UG › Physics › System of Particles and Rotational Motion › For a rigid body, the centre of mass moves as th…
For a rigid body, the centre of mass moves as though the body's total mass were concentrated there and all external forces acted on it. This statement is:
AAlways true
BTrue only for non-rotating bodies
CTrue only in uniform gravity
DNot true in general
Answer & Solution
Correct answer: A. Always true
1. From Newton's second law applied to each particle and summing, internal forces cancel in pairs (third law).
2. The resultant becomes M (d²R_cm/dt²) = ΣF_ext.
3. So the centre of mass moves as if all mass were there and only external forces acted — true for ANY system of particles.
_Source: NCERT Class 11 Physics Ch 6 §6.4 CM Motion_
Related questions
The radius of gyration k of a body about an axis is defined so that:Two bodies have the same angular momentum L. The one with the LARGER moment of inertia hasA wheel rolls without slipping with the centre of mass having velocity v. The instantaneouA solid sphere of mass M and radius R has moment of inertia about a diameter:A flywheel of moment of inertia 2 kg m² rotates at 60 rpm. The torque required to bring itAn ice skater spinning with arms outstretched pulls her arms in. Her angular speed:Total kinetic energy of a body rolling without slipping is:A solid disc and a hollow ring of the same mass and radius roll without slipping down the