Intuition might tell us that rough surfaces on clothing would inhibit the speed of an olympic athlete. why is this line of thinking not true in some cases? how can controlled roughness actually promote speed?

We associate roughness with a greater coefficient of friction, then we think that rough surfaces on clothing would inhibit the speed of an Olympic athlete.  This is not always true because the amount of roughness might improve the way air pass through the fabric.  

One example of controlled roughness that actually promote speed are the dimples on golf balls. Dimples create turbulence around the ball, which sucks air to the ball, making its displacement easier and promoting its speed.

a charge 3q is at the origin, and a charge −2q is on the positive x axis at x=a. part a where on the x-axis would you place a third charge so it would experience no net electric force? enter an expression for the exact answer, which will involve a square-root sign. (do not enter an approximate decimal answer.)

get the total number of pieces of fruit and divide it by 4 to get the average. the result is the answer to the problem. 14 total number of fruits and there are 4 members. 14 divided by 4 is equals to 3.5.