A projectile is shot horizontally at a speed of 16 m/s and hits a target at 21.7m away. What was the initial height of the canon?

It is really hard for me right know

Explain what happens at the saturation point when adding salt to water at room temperature.

The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. find the period when the length is 144 cm and the acceleration due to gravity is 980 cm per second squared, if the period is 7pi seconds when the length is 289 cm and the acceleration due to gravity is 980 cm per second squared.