Question

When you drop a penny off the roof of a building, it takes 10 seconds to reach the ground. How high is the roof?

Answer 1

D = (1/2) (g) (t²) <== Memorize this. All the rest is just arithmetic.

D = (1/2) (9.8 m/s²) (100 s²)

D = (1/2 x 9.8 x 100) (m-s²/s²)

D = (4.9 x 100) m

D = 490 meters