What are the bumps on a gear called?

The density of a liquid could be found by using

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?

Suppose a soccer ball is kicked from the ground at an angle 20.0º above the horizontal at 8.00 m/s. the y-velocity is determined to be 2.74 m/s. how long will the ball be in the air? assume the ball lands at the same height at which it was kicked.