Astorm blows wind across the top of a roof at a speed of v = 26.3 m/s. assume the air on the lower side of the roof (inside) is at rest and the roof is flat and has an area a = 38.9 m². the density of air is 1.28 kg/m³.1) what is the pressure differential across the top and bottom of the roof? 2) what is the net lift force on the roof due to the storm?

Examine the equation. 23490th→23088ra+42he what kind of barrier would you need to block the radioactive particles from this reaction? a.a piece of paper b.a sheet of aluminum foil c. a two-inch block of lead d. a solid concrete block

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.

What is friction? how does it affect the motion of an object?