A taut string of length 1.0 m is holding a yo-yo of mass 130 g. You notice from flicking the top of the string that the pulse takes 66 ms to travel down to the yo-yo. What is the mass of the string

If there was no gravity then their would be no downword force on the football to have it return the the grownd, and if there was no friction (mainly air friction) then there would be no opposing force the stop the ball from moving through the air allowing the ball to travle ∞.

A. they hold atoms  together with a molecule.its a force that exist between molecules. hope this .

490 n  f=125n a=2.5m/s2

Ke reqd to move from 0 to 50 will be proportional to 50x50 or 2500. this is equal to w.  to change vel from 50 to 150 you need energy prop to 22500 - 2500 = 20,000. this corresponds to 8w.  best answer is a) . work reqd is prop to velocity squared.