## Thermodynamics: An Engineering Approach 8th Edition

$a=56.88\frac{m}{s^2}$
First we calculate the weight force: $W=mg=(3kg)*(9.79\frac{m}{s^2})=29.37N$ Then the net force acting on the rock upside direction is: $F_{net}=F_{up}-F_{weight}=200N-29.37N=170.63N$ Now we have the net force we can calculate the acceleration according to the Newton's second law: $a=\frac{F}{m}=\frac{170.63N}{3kg}=56.88\frac{m}{s^2}$