State the basic assumptions of the kinetic theory. a- All matter is composed of small particles;

b- The particles are in constant motion;

c- Molecules are smaller than atoms.

d- The energy lost in the collisions is negligible.

e- These particles are constantly colliding;

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?