Answer
$$m= \frac{2k}{v^2} $$
Work Step by Step
We multiply both sides by $2$ and then we divide by $v^2$ as follows:
$$2k=mv^2 \Longrightarrow \frac{2k}{v^2}= \frac{v^2m}{v^2} \Longrightarrow m= \frac{2k}{v^2} .$$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.