Physics-
General
Easy
Question
Two small particles of equal masses start moving in opposite directions from a point
in a horizontal circular orbit. Their tangential velocities are
and
, respectively, as shown in the figure. Between collisions, the particles move with constant speeds. After making how many elastic collisions, other than that at
, these two particles will again reach the point 

- 4
- 3
- 2
- 1
The correct answer is: 2
Let initially particle
is moving in anticlockwise direction and
in clockwise direction
As the ratio of velocities of
and
particles are
, therefore ratio of their distance covered will be in the ratio of
. It means they collide at point B

After first collision at B, velocities of particles get interchanged,
.,
will move with
and particle
with 
Second collision will take place at point C. Again at this point velocities get interchanged and third collision take place at point A
So, after two collision these two particles will again reach the point A
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