A 7.50 kg disk with a diameter of 88.0 cm is spinning at a rate of 280 revolutions per minute. A block of wood is pressed into the edge of the disk with a force of 35.0 N. The coefficient of friction between the wood and the disk is 0.300. How long does it take the disk to stop spinning?

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

The radius of an atom is closest in size to a

At the point of fission, a nucleus of ^235 u that has 92 protons is divided into two smaller spheres, each of which has 46 protons and a radius of 5.90 x 10 ^-15m. what is the magnitude of the repulsive force pushing these two spheres apart