While eating a peanut butter and jelly sandwich, peanut butter drips on Diana’s shirt. She tries to remove the peanut butter from her shirt by rubbing the spot with water, but it doesn’t work. What is the best explanation for why the water does not remove the peanut butter? The water and peanut butter have different chemical properties.
The water and peanut butter have different temperatures.
The water and peanut butter have different pressures.

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.