Please help me with this

How many cells are our body made of ? ♡

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his 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

The law of thermodynamics states that energy can't be created or destroyed. to natural sources of energy on earth are the