# Hint needed

1. Dec 17, 2005

### vaishakh

Can anyone here give some hint to solve this question. I cannot proceed much in solving this question.
Point A moves with constant velocity v so that the vector v is continually pointed towards the point B which in turn is in a rectilinear motion with a uniform velocity u < v. at the initial moment of time vector v is perpendicular to the vector u and the points are separated by a distance of l. how soon the points will converge?

The problem that I face with this problem is that there is no definition of when does A start turning and what will be the direction and the distance between A and B when A starts turning. Infact A turns constantly(I know that).

2. Dec 17, 2005

### Staff: Mentor

A starts turning when B is moving. Remember, the vector v is always pointing from A to B, and B is moving with speed u.

I can think of the case where v is the constant velocity on a circular arc of radius l.

v and u are uniform. Also, v2= vx2(t) + vy2(t)

In order to meet, pt A and B, must traverse the same distance in the same time, so <vy> = u during the same period.

Last edited: Dec 17, 2005
3. Dec 20, 2005

### mukundpa

Let u is along x
at time t, v makes theeta with u

1. in time interval t the relative distance covered in x direction is zero

2 in time interval t distance covered by A relative to B along AB = l

the tric is in integrals

try a good question!

Dont see the back of I.E. Erodov

MP