A box is at rest on the floor. The mass of the box is 150 kg and the coefficient of static friction between
the box and the floor is 0.30. The maximum force of
static friction is approximately

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

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.