The diagram shown below illustrates the problem. v = vertical upward launch velocity. g = 9.8 m/s² is acceleration due to gravity.
When s = - 35m, the elapsed time is 4 s. Therefore (- 35 m) = (v m/s)*(4 s) - (1/2)*(9.8 m/s²)*(4 s)² -35 = 4v - 78.4 4v = 78.4 - 35 = 43.4 v = 10.85 m/s
Here yo = 35.0m Vo is unknown y final = 0 t = 4.00 s and I will approximate g to 10m/s^2
=> 0 = 35.0 + Vo * 4 - 5 * (4.00)^2 => Vo = [-35 + 5*16] / 4 = - 45 / 4 = -11.25 m/s
The negative sign is due to the fact that the initial velocity is upwards and we assumed that the direction downwards was positive when used g = 10m/s^2.
The dolphin would send an underwater message because the water is denser than air and therefore the sound would be louder and would travel faster. The denser the object the faster the sound travels.
