Percentage errors in the measurement of mass and speed are 2% and 3% respectively. The error in the estimate of kinetic energy obtained by measuring mass and speed will be: [PMT/NEET-1995]

a. 8%
b. 2%
c. 12%
d. 10%

Answer: a. 8%

Solution:
Kinetic energy

$$ K=\dfrac{1}{2}mv^{2} $$

Relative error:

$$ \dfrac{\Delta K}{K}=\dfrac{\Delta m}{m}+2\dfrac{\Delta v}{v} $$

$$ =2\%+2\times 3\%=8\% $$