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When both mass and velocity are measured, the uncertainty in kinetic energy is found by adding the two uncertainty sources in quadrature. You compute the partial derivative of kinetic energy with respect to each variable, multiply each derivative by the corresponding absolute uncertainty, square those terms, sum them, and take the square root.

Conditions: The kinetic energy formula is $K = \frac{1}{2}mv^2$.; Both mass $m$ and velocity $v$ carry independent absolute uncertainties $\delta m$ and $\delta v$.; The uncertainties are small enough for a first-order linear approximation.

When both mass and velocity are measured, the uncertainty in kinetic energy is found by adding the two uncertainty sources in quadrature. You compute the partial derivative of kinetic energy with respect to each variable, multiply each derivative by the corresponding absolute uncertainty, square those terms, sum them, and take the square root.

Conditions: The kinetic energy formula is $K = \frac{1}{2}mv^2$.; Both mass $m$ and velocity $v$ carry independent absolute uncertainties $\delta m$ and $\delta v$.; The uncertainties are small enough for a first-order linear approximation.