Two identical discs of same radius `R` are rotating about their axes in opposite directions with the same constant angular speed `omega` . The discs are in the same horizontal plane. At time `t = 0` , the points `P` and `Q` are facing each other as shown in the figure. The relative speed between the two points `P` and `Q` is `v_(r)`. In one time period `(T) ` of rotation of the discs , `v_(r)` as a function of time is best represented by

Options

A.
B.
C.
D.

Answer

a

Explanation

So, `v_(4)=2omegaRsin (omegat)`
At t=T/2, `V_(r)=0`
So two half cycles will take place.
(a) directily at the target (b) 5cm below the target
(c) 5 cm above the target (d) 2 cm above the target
(e) 2 cm below the target.