## Physics: Principles with Applications (7th Edition)

$0.435 \frac{m}{s^{2}}$ in the upward direction.
Apply Newton’s second law to the elevator. Choose up to be the positive direction. $$\Sigma F=F_t – mg = ma$$ $$a = \frac{ F_t-mg}{m} =\frac{21750 N-(2125 kg)(9.80 \frac{m}{s^{2}})}{2125 kg} \approx 0.435 \frac{m}{s^{2}}$$ The answer is rounded to 3 significant figures. The positive sign confirms that the acceleration is upward.