Question

two masses M1 and M2 connected by a spring of spring constant k rest on a frictionless surface if the masses are pulled apart and let go the time period of oscillation is​

Answer 1

T = 2∏ √{[ ( m 1 ∗ m 2 ) / ( m 1 + m 2 )](1 / k)}

I don't know the derivation but this is the straight forward formula.

Hole this helps