Answer:
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:
[tex]v_f=v_o+g.t[/tex]
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:
[tex]v_f=7.2~m/s+9.8~m/s^2*4~s[/tex]
Calculating:
[tex]v_f=46.4~m/s[/tex]
The speed after 4 seconds is 46.4 m/s
