Question

At time t = 0 s, apple 1 is dropped from a bridge onto a roadway beneath the bridge; somewhat later, apple 2 is thrown down from the same height. The figure gives the vertical positions y of the apples versus t during the falling, until both apples have hit the roadway. The scaling is set by ts = 2.0 s. With approximately what speed is apple 2 thrown down?

0.5 1.5 2.5 (s)

Answer 1

The first apple takes 2 seconds to fall, so the bridge height is

h = 1/2gt^2

h = 1/2 x 9.8m/s^2 x (2s)^2

h = 19.6 meters

The second apple takes 1.25 seconds to fall, so we have

19.6 m = v x 1.25s + 1/2 * 9.8m/s^2 * (1.25s)^2

v = 9.6 m/s