تمرین ۱۲ $Q_{1} + Q_{2} + Q_{3} + Q_{4} = 0$ $m_{1}c_{1}(\theta_{e} - \theta_{1}) + m_{2}c_{2}(\theta_{e} - \theta_{2}) + m_{3}c_{3}(\theta_{e} - \theta_{3}) + m_{4}c_{4}(\theta_{e} - \theta_{4}) = 0$ $300 \times 0.384(52 - 30) + 80 \times C_{x}(52 - 30) + 50 \times 4.2(52 - 20) + 100 \times 4.2(52 - 75) = 0$ $C = 0.7 \frac{J}{g} = 700 \frac{J}{kg}$