A trombone has a variable length. When a musician blows into the mouthpiece and causes air in the tube of the horn to vibrate, the waves set up by the vibrations reflect back and forth in the horn to create standing waves. As the length of horn is made shorter, what happens to the frequency?

The frequency increases.

Explanation:

When the Musician draws the slide in the length of the horn gets shorter, which causes a decrease in the wavelength. A decrease in the wave length results in an increase in frequency.

Note:

The diameter of the horn has an effect on frequency, so a wider horn is effectively a long horn - open end correction ( distance between the the antinode and the open end of a pipe).

Frequency also depends on how hard the musician blows the trombone. The musician can change the frequency with the lip pressure being applied.

i think the answer is b

moving ball hits still ball. mover stops, hit ball moves. momentum transfer.