A ball of mass m moving with velocity v strikes the bob of a...

A ball of mass $\text{m}$ moving with velocity $\text{v}$ strikes the bob of a pendulum at rest. The mass of the bob is also $\text{m}$. If the collision is perfectly inelastic, the height to which the bob will rise is given by~<!-- MathType@Translator@5@5@MathML2 (namespace attr).tdl@MathML 2.0 (namespace attr)@ --> $\text{h =}\dfrac{v^{2}}{\text{x}\text{.g}} \text{,}$ <!-- MathType@End@5@5@ --> then <!-- MathType@Translator@5@5@MathML2 (namespace attr).tdl@MathML 2.0 (namespace attr)@ --> $\text{x} = ?$ <!-- MathType@End@5@5@ -->