The diagram from bellow shows a bullet which strikes a block hanging from a ceiling. The mass of the block is $20\,g$. Such bullet impacts to the block of mass of $980\,g$ and gets embedded on it. Find the angle that deflects the maximum from the vertical. You may use $g= 10 \,\frac{m}{s}$

The alternatives given are:

$\begin{array}{ll}

1.&20^{\circ}\\

2.&30^{\circ}\\

3.&37^{\circ}\\

4.&53^{\circ}\\

5.&60^{\circ}\\

\end{array}$

I'm stuck on this problem. What I attempted to do was to use the principle of conservation of momentum for an inelastic collision as follows:

$p_i=p_f$

Therefore

$mv_1=\left(m_1+m_2\right)v_2$

$20\times 50 = (20+980)v_f$

$v_f=1\,\frac{m}{s}$

But I'm stuck on how to find the angle can someone help me with this please?.