Do EM Waves need matter in order for them to go from one place to another?

Sound wave is a mechanical wave . Some material quantity is needed in order for a sound wave to propagate by compression and rare faction of the medium entity involved. An electromagnetic wave requires no medium as electric fields and magnetic fields constantly generate each other as the wave propagates. This comes through the maxwell equations that a changing magnetic field produces an electric field and vice versa.

it has to be b, about 97 percent.

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.