What two features would make humans good index fossils

How is the motion of the particles of water at 80 ⁰c different from the motion of the particles of water when it is 30 ⁰c?

Acceleration is a direct result of a.) balanced forces b.) unbalanced forces c.) gravity d.) velocity

Johnny rode his bike 4 blicks down the street to his friend's house once he got to his friend house and realized he could not cone out to play he turned aroubd and went back home.what is displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point