Pressure Notes PDF

1 Even both metal blocks have the same weight, which means (they apply the same amount of force on sand), they sink in the sand to different depth. Even both hammers hit the nails with same force the sh...

1 Even both metal blocks have the same weight, which means (they apply the same amount of force on sand), they sink in the sand to different depth. Even both hammers hit the nails with same force the sharper nail went deeper into the wooden block.  1 Pascal = 1 N/m2.  Pascal symbol is (Pa).  If force (weight) increases pressure increases.  If area increases pressure decreases.  Pressure: is the force applied per unit area. 1- Liquid pressure acts in all directions. 2- As depth increases, liquid pressure increases. 3- As density of liquid increases, liquid pressure increases. 4- P = ρ g h. 5- Points at same level have same pressure. Pressure 36  2 Unlike molecules of solids that vibrate in position, liquid molecules have a little more freedom to move, they can slide over each other in all directions. Liquids can flow in all direction because of liquid pressure. Both divers have a pressure gauge to measure the pressure under water the diver at greater depth is under greater pressure than the other at smaller depth does. Mercury is denser than water if pressure is measured at the same depth in both liquids, pressure in mercury will be higher. P: pressure (Pa), ρ: density of the liquid (kg/m3), g: 10 m/s2, h: depth (m) Even one diver is in the cave and the other diver is out of the cave Pressures on both divers are equal as long as they are in the same container. Pressure 37  3 Moving gas molecules collide with the inner walls of the container. These collisions cause change in momentum of gas molecules. Change in momentum/time = force on the inner walls of the container. The force applied per unit area is the pressure of the gas. The weight of atmospheric air above us exerts pressure on everything on earth  As we go higher, atmospheric pressure decreases, because the height of air column will decrease.  The pressure on a diver is the water pressure above him + atmospheric pressure.  In the collapsing can experiment air is pumped out of the can until it collapses.  The can collapses because the number of air molecules inside the can decreases so the frequency of collisions with the inner walls of the can decreases, this causes the pressure inside the can to be smaller than atmospheric pressure outside the can so it collapse. Pressure 38 When an Object moves in circular motion it accelerates even it is moving with constant speed Explanation. Acceleration is the change in velocity. Velocity is vector ( Changes by changing direction ). As direction changes the velocity changes. So the object accelerates even tho it is moving with constant speed Centripetal Force - A force that continuously changes the direction of the object and keep it moving in a circular path