### Elevator

Solve the problem out of order (switch the order of the questions). (b) The time to fall is $t=\sqrt{\frac{2y}{a_{y}}}=\sqrt{\frac{2(-120m)}{(-9.8m/s^{2})}}=4.9s.$
(a) The speed at which the elevator hits the ground is $v_{y}=a_{y}t=(-9.8\frac{m}{s^{2}})(4.9s)=48\frac{m}{s}.$
(d) The time to fall halfway is $t=\sqrt{\frac{2y}{a_{y}}}=\sqrt{\frac{2(-60m)}{(-9.8m/s^{2})}}=3.5s.$
(c) The speed at the half-way point is $v_{y}=a_{y}t=(-9.8\frac{m}{s^{2}})(3.5s)=34\frac{m}{s}.$