IIT JEE , AIEEE Forum - Physics , Mechanics

kislay

3. At the initial moment three points A,B and C are on a horizontal straight line at equal distances from one another. Point

A begins to move vetically upward with a constant velocity v and point C vertically downward without any initial velocity but

with a constant acceleration a. How should point B move vertically for all the three points to be constantly on one straight

line. The points begin to move simultaneously.

krishna.gopal

Let initialy cordinats of A, B, C are (-b,0), (0,0) and (b,0).(x-axis horizontal y-axis vertical)

At any time t A = (-b,ut) and C=(+b,0.5at^2)
If ABC are in straight line and B is on y-axis so cordinates of B are (0, (ut-0.5a^2)/2)

So b should move with an initial velocity of u/2 in upward direction with a constant acceleration of a/2 in downward direction

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