A box weighing 30 N is on a horizontal floor. The coefficient of static friction is 0.30 and that of kinetic friction is 0.25. Find the frictional force under the following conditions: a) no additional forced is added, b) a force of 5 N is applied to the east, c) a force of 9 N is applied to the west, d) a force of 10 N is applied to the south.

What is the coefficient of kinetic friction μk between the block and the tabletop?

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.

Mark creates a graphic organizer to review his notes aboutelectrical force. which labels belong in the regions marked x and y?