Compute the angular velocity of bar:

A bar AB as shown in slides so that its bottom point A has a velocity of 4 m/sec to the left along the horizontal plane. Compute the velocity of B and also the angular velocity ω. (by velocity diagram method).

We have

 v _B  = v _A  + v _AB  (where, v_AB is perpendicular to AB)

Solution

Select any point O. Draw v_A to scale (oa). Draw a line along which vB lies. From a, draw vAB in a direction perpendicular to AB where it cuts the line drawn from O along O b. Name it b. Refer Figure (b).

Then Ob represents V_B and ab represents v_AB.

∴          v _A / sin 60^o =   v_B /sin 75^o =     v _AB /sin 45^o

∴ v_B  = 4.46 m / sec ; v_AB = 3.265 m/s

ω = v _AB / AB

= 3.265 rad / sec