\(\displaystyle u_1=10ms^{-1}\)

\(\displaystyle m_2=2kg\)

\(\displaystyle u_2=0\)

The collision is elastic.

Find:

\(\displaystyle v_1\) and \(\displaystyle v_2\)

By using total kinetic energy is conserved, I get 2 sets of answer.

\(\displaystyle v_1=10\) , \(\displaystyle v_2=0\)

\(\displaystyle v_1=2\) , \(\displaystyle v_2=12\)

Which is the correct answer?Or both are acceptable?