Question

8
Two men A and B are sitting at the end of a plank of length L, if plank is
rotating with angular velocity o about an axis perpendicular to its length
and passing through a point at a distance of L/3 from A. The angular A
velocity of B with respect to A is
(A) o
(B) OL/3
20
(C)
(D) 20
3​

Answer 1

Given:

Length of the plank = L

Angular velocity of plank = o

Distance of axis from A = L/3

To find:

The angular velocity of B w.r.t. A.

Solution:

Since A is at a distance of L/3 from the axis, then B will be at a distance of 2L/3 from the axis as the total length is L.

Distance from B after taking symmetry conditions = L- (L+L)/3 = L - 2L/3 = L/3

So angular velocity of A w.r.t B = o*L/3 = oL/3.

Therefore the correct option is B i.e. oL/3.