A 5.0 kg mass with an initial velocity of 4.0 m/s in the +x direction collides with a 4.0 kg mass with an initial velocity of 3.0 m/s in the x direction. After the collision, the 5.0 kg mass has a velocity of 1.2 m/s in the +x direction. What is the magnitude of the velocity of the 4.0 kg mass after the collision? (Hint: momentum is conserved, but energy is not.)

Can someone explain to me how to do this problem ?

Ascrew incorporates which other simple machine? lever wheel and axle inclined plane pulley

Although longitudinal waves can travel through all media types what is the disadvantage of this type of wave transmission? a) he efficiency of he wave transmission is greatly diminished as the media becomes less dense b) the oscillation of one set of particles has a huge impact on neighboring particles c) particles become too close together as they bump into each other making it more likely to hit other particles down the line