Achild aims his air rifle at an angle of 10 degrees above the horizontal. he fires a bb while simultaneously dropping another b-b from rest, from the same height as the rifle barrel. which b-b will hit the ground first

The b-b at rest will hit the ground first

Explanation:

When the first b-b is shot at angle it will first experience some horizontal force of air resistance before it experience another vertical force of resistance when going done while the second b-b only experiences the vertical force of resistance making reach the ground faster.

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

layers of the earth affect the waves and these effects are seen on instruiments such as seimometers