Answer: Solids
Explanation: Solids have very little movement and the particles have barely enough movement to vibrate. We can't see it but the particles are indeed vibrating. Solids have the least amount of kinetic energy which is moving energy.
Because the atoms and molecules all have different properties
Answer:
Zero
Explanation:
Average velocity is given by:

where
d is the displacement of the trip
t is the time it takes for the trip to complete
In this problem, the net displacement of the swimmer is zero. In fact:
- First, he swims 30.0 m in the north direction
- Then, he travels back (-30.0 m) in the south direction, to the starting position
Since the final position is equal to the starting position, the displacement is zero:
d = 0
And therefore, the average velocity is also zero.