Question

An object is dropped from a bridge. A second object is thrown downwards 1.0 s later. They both reach the water 20 m below at the same instant. What was the initial speed of the second object? Neglect air resistance.

Answer 1

Answer:

15m/s

Explanation:

$20m = \frac{1}{2} g {t}^{2} \\ t = 2s \\ t0 = 2s - 1s = 1s \\ vt + \frac{1}{2} g {t}^{2} = 20m \\ v \times 1s + \frac{1}{2} \times 10 \times 1 = 20 \\ v = 15$