If you push a box across the floor, the box experiences what kind of friction? cohesive friction rolling friction static friction kinetic friction potential friction

For this situation the right answer is d, the kinetic friction, because in this case we are talking about moving surfaces: the surface of the box moving along the surface of the floor.

When this happens there may be a force that acts in opposite direction to the movement of the box and tends to stop it (Friction).

The other options are not correct because:

a)The cohesive friction does not exist

b)The Rolling Friction applies for a body that rolls on a surface (an object with the shape of a circumference for example), and in this case the situation described is with a box

c)Static Friction is the friction in a body that keeps at rest. In this situation is not applied because the body is in motion

d)Potencial friction does not exist  

0.55x745.7j and a calculator

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s