Question

When two links are parallel then thier velocities are same

Answer 1

Suppose the position vector of A be x⃗  and the position vector of B be y⃗  . Suppose the points start moving with velocities v⃗ 1 and v⃗ 2 respectively. Then at any instant of time t the positions of the two points will be x⃗ +tv⃗ 1 and y⃗ +tv⃗ 2 respectively. If the points meet at some instant of time T then at that instant their positions must be same, i.e., we must have

Answer 2

Yes that's true....