A student drops a rock off a bridge. The rock has a mass of 5.81 kg. If the bridge is 48.7 m high, how much time does it take it to reach the water below?

To calculate the time it takes for the rock to reach the water below, we can use the principles of free fall motion. The time can be found using the equation:

t = sqrt(2h/g)

where t is the time, h is the height of the bridge, and g is the acceleration due to gravity.

First, let's determine the value of g, which is approximately 9.8 m/s² on Earth. Now we can substitute the given values into the equation:

t = sqrt(2 * 48.7 m / 9.8 m/s²)

Calculating this further:

t = sqrt(98 m / 9.8 m/s²)

t = sqrt(10 s²)

t = 3.16 s

Therefore, it takes approximately 3.16 seconds for the rock to reach the water below.