What is pitch?? what is the use of it

Pitch is defined as the sharpness of sound.

Pitch in sound corresponds to colour in light which depends on the wavelength or frequency of a light wave.

The use of the pitch is that it enables us to distinguish between a high, acute or shrill note from low, grave or flat note.

Hope it will help you.

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.