What sets an atom of one element apart from atoms of all other elements?

The number of protons in the nucleus make one element different from another element.

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )