A girl standing on a bridge throws a stone vertically downward with an initial velocity of 15.0 m/s into the river below. If the stone hits the water 2.00 seconds later, what is the height of the bridge above the water

the height of the bridge above the water is 49.6 m.

Explanation:

Given;

initial velocity of the stone, u = 15 m/s

time of motion of the stone, t = 2 s

The height of the bridge above the water is calculated from the following kinematic equation as follows;

h = ut + ¹/₂gt²

h = (15 x 2) + ¹/₂(9.8)(2²)

h = 30 + 19.6

h = 49.6 m

Therefore, the height of the bridge above the water is 49.6 m.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me