Write the negative impacts of waves on. human health??listed Some more points

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

The discovery of the electron as a subatomic particle was a result of

According to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does maria's voyage take according to samir?