physics/math
posted by kristin on .
Joe is a former basketball player who is now a workout junkie, and especially loves to do pushups. He was a good athlete, but not so good at science in school, especally not good in Physics. He wants you, yes you, to calculate how much work he does, in strict terms of Physics, when he does his pushups.
Joe is exactly 2 metes tall. His center of gravity is in the middle, one meter from either end. When he places his hands to do pushups, they are 1.5 meters from his toes. He has long arms, so when he raises himself up all the way off the floor, his center of gravity is exactly one meter off the floor (OK, that makes him built like an orangutan, give me a break, I'm trying to keep the numbers simple). How much work would he do, in Joules, of course, if he does 100 pushups? Remember, the acceleration of gravity is 9.8 meters per second squared.

How about if you, yes you, do the calculations? It is you who is taking the course.
Where he places his hands doesn't matter. We will have to assume that his center of gravity is at floor level at the bottom of his pushups, although this cannot be strictly true.
Calculate how far he raises his body with each pushup, and multiply that by m g x 100. 
Here is the problem
A typical atom has a diameter of about 1.0 X 10^10m. What it is in inches?
How many atoms are there along a 1.0 cm line?
( I got the first part but confuse w/ the second part. how do I know how many atoms are there? Please help me)