Question

How long does it take an acorn to hit the ground after dropping from the branch of a tree 12.5 m high? Remember that g=9.8 m/s^2!

1.0 s, 5.0 s, 2.6 s, or 1.6 s

**not sure about this!! :(

Answer 1

The answer is 1.6 s

The kinetic formula that can be used is:
d = v1 * t + 1/2 a * t²

d - distance
v1 - initial velocity
t - time
a - gravitational acceleration

We have:
d = 12.5 m
v1 = 0 (in free fall)
t = ?
a = 9.8 m/s²

d = v1 * t + 1/2 a * t²
12.5 = 0 * t + 1/2 * 9.8 * t²
12.5 = 0 + 4.9 * t²
12.5 = 4.9 * t²

t² = 12.5/4.9
t² = 2.55
t = √2.55
t = 1.6 s