75. We choose downas the +ydirection and use the equations of Table 2-1 (replacing xwithy) with a= +g,v0= 0 and y0= 0. We use subscript 2 for the elevator reaching the ground and 1 for the halfway point. (a) Eq. 2-16, vvayy2202202=+−bg, leads to ()22222 9.8 m/s120 m48.5 m/s .vgy===(b) The time at which it strikes the ground is (using Eq. 2-15)
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