Conservation of linear momentum collision

[_buddha]

Homework Statement

A 2.0 kg object moving along the x-axis at 3.0 m/s strikes a 1.0 kg object initially at rest. Immediately after the collision, the 2.0 kg object has a velocity of 1.5 m/s directed 30 degree from its initial direction of motion. What is the x-component of the veolcity of the 1.0 kg object just after the collision?

Homework Equations

pi = pf

The Attempt at a Solution

m1v1i + 0 = m1v1f + m2v2f
2(3) = 2(1.5cos30) + (1)vf
vf = 2.4 m/s

thats what i get, but the answer is 3.4 m/s. What am i doing wrong here?

 

[Shivpal]

You are doing it correctly, calculate the vf again from your last equation it is coming out to be 3.4m/s. vf= 2(3)-2(1.5*\sqrt{3}/2) = 6 - 2.6 = 3.4