water flows through a pipe that gradually descends from a height of 6.78 m to the ground. near the top, the cross-sectional area is 0.4 m2, and the pipe gradually widens so that its area near the ground is 0.8 m2. water leaves the pipe at a speed of 16.8 m/s. what is the difference in the water pressure between the top and bottom of the pipe?

Iwill give brainliest if you answer right : )

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.

Ryan is examining the energy of the particles in a bar of gold. what is ryan most likely studying?