A stone is thrown down off a bridge with a velocity of 7.2 m/s what is its velocity after 4 seconds

The speed after 4 seconds is 46.4 m/s

Explanation:

Vertical Launch Downwards

In a vertical launch downwards, an object is launched vertically down from a height H without taking into consideration any kind of friction with the air.

The final speed is calculated by using the formula:

Where:

vf = Final speed

vo = Initial speed

g = Acceleration of gravity (9.8~m/s^2)

t = Elapsed time

The stone is thrown down off a bridge at vo=7.2 m/s. We need to calculate the speed after t=4 seconds.

Substituting:

Calculating:

The speed after 4 seconds is 46.4 m/s