24I still havent been able to understand this ques.....even after 5months..
plzz someone explain it to me in very simple language..
Two small particles of equal mass start moving in oppsotite directionds from a point A in a horizontal circular orbit. Their tangential velocities are v adn 2v respectively, as shown in the figure. Between collisions, the particles move with constant speeds. After making how many elastic collisions, other than that at A, these two particles will again reach the point A?
A) 4 B)3 C) 2 D)1
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7 Answers
62[url=http://iitjee2009solutions.targetiit.com]Solution Key with Question Paper of 2009 IIT JEE[/url]
24
3since massses are same,velocities get interchanged when they collide each other.
let collison happens at time t.
so for particle with velocity v.
rθ1=vt
for the other on
rθ2=2vt
and θ1+θ2=2π find θ1 and θ2
similarly find the coordinates of the particle at the second collision and find the coordinate of the particle at the third collision.
1well during iit i did this question by common sense
assume the circle to be of three units
now before 1st collision the 1st particle will travel 1 unit and the second particle wll travel 2 unit distance(as their velocities are in the ratio 1:2
now after 1st collision their velocities will exchange and now they will travel in opposite directions with velocities in the ratio 2:1
now
now before 2nd collision the 1st particle will travel 2 unit in opposite direction and the second particle wll travel 1 unit distance in opposite direction and hence they will meet at point of second collision
after 2nd collision the velocities will again exchange and hence they will meet at a........
i know my approach is not correct but it saves time........