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:

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.