# Conservation of momentum - finding the angle between broken parts

Let a stationary block explodes into 3 equal pieces .The speeds are also equal which is $v$. If I am asked to determine the angle between the broken pieces that are moving then how to deal with this problem? Because the system must obey the conservation of momentum, can the velocity vectors be arranged by a equilateral triangle?

If the speed or mass varies then what changes of the angles will happen between them? Is there any unique way to solve this type of problem?

For example, with $\alpha = 120 \text { degrees}$, the balance of momenta is on the vertical direction:
$m_1v_1=m_2v_2\cos60 + m_3v_3\cos60$, with $\cos60=0.5$ and $m_1=m_2=m_3$ and $v_1=v_2=v_3$ then this is always true.