A soccer ball and a volley ball moved in a plane surface very fast. If the two balls moved at the same speed, which of the two balls id difficult to stop?

Wow good luck with that answer

. we do not care the other details; the average velocity is only concerned with the  displacement rather than the  distance traveled. displacement is the change in position, or the "straight-line vector from the initial position to final position".

This is actually a calculus question. so, basically, this is a related rates question where you are given 1 quantity and you have to find the other.  we'll define some variables first.x = 9 ftdx/dt = 7 ft/secl = 15 ftsince you want to find the area, you have to find a formula for it. which is: we know the base (x), but we don't know the height (h). we can figure it out by solving for it. we have to form an equation which we can figure out height from given the information we have. this equation is: plug in known values: solve for h: now, let's solve for the rate at which h is changing. we can do so by differentiating the pythagorean theorem (above). let's do that: plug in values: now we have all the given information to do this problem. so, to figure out the rate of change of area, we can differentiate (with respect to time) the earlier equation: which is equal to: plug in known values: so, the area of the triangle is changing at approximately 18.375ft²/sechope this all makes sense. if it doesn't, either contact me, or watch khan academy - he explains it real well. special credit to turtaniumx and quietself for letting me know of the error, and fix it!