Question

A stone fell from the top of a cliff into the ocean.

In the air, it had an average speed of 16 m/s. In the water, it had an average speed of 3 m/s, before hitting the seabed. The total distance from the top of the cliff to the seabed is 127 meters, and the stone's entire fall took 12 seconds.
How long did the stone fall in the air and how long did it fall in the water?

Answer 1

Time the stone fall in the air = 7 seconds

Time it fall in the water = 5 seconds

Explanation:

Given in the question,

speed of stone in the air = 16 m/s

speed of stone in the water = 3m/s

The total distance from the top of the cliff to the seabed = 127 m

the total time it took to hit the seabed = 12 s

Suppose time took to hit the water = x

so the time took from top of water to seabed = 12 - x

Formula to use

distance = speed x time

Total distance = first distance + second distance

127 = 16x + 3(12-x)

127 = 16x + 36 - 3x

127 - 36 = 16x - 3x

91 = 13x

x = 91/13

x = 7 seconds

12 - x = 12 - 7 = 5 seconds