Three guns are aimed at the center of a circle, and each fires a bullet simultaneously. the directions in which they fire are 120° apart. two of the bullets have the same mass of 5.79 x 10-3 kg and the same speed of 392 m/s. the other bullet has an unknown mass and a speed of 605 m/s. the bullets collide at the center and mash into a stationary lump. what is the unknown mass?

The unknown mass of the bullet is  

Explanation:

According to Newton's laws of motion, when a net external force acts on a body of mass  m , it results in change in momentum of the body and is given by:

Where:

P

is the linear momentum of the body

As a consequence, when there are no external forces acting on the body the total momentum remains conserved i.e.

Given:

For momentum along the y-direction to be zero, it is achieved when the equal masses are moving at angles of  

θ1=180°, θ2=60°, θ3=-60°

Therefore, from conservation of momentum along x - direction:

i think the answer is a and b

i wish you luck