pressure Flashcards
Definition of pressure
pressure is the force exerted per unit area
definition of atmospheric pressure
pressure exerted on Earth’s surface by the atmosphere
explain how a hydraulic press works
as liquids cannot be compressed, pressure at one end of piston = pressure at the other end therefore pressure can be transmitted from one piston to the other, through the liquid.
This allows hydraulic press to produce a greater force at the larger piston from applying a smaller force at the smaller piston
explain why does a hydraulic pressure does not work well when its oil contains air
energy would have been done by Piston X to compress the air bubbles therefore more bubbles used and less energy used to do work therefore the hydraulic pressure is less efficient
describe how distance moved by piston A compares to distance moved by piston B in a hydraulic press
By Conservation of energy , work done by piston=on A is equal to work done by piston B
base area of piston B greater than piston A therefore distance moved by piston B is shorter.
what happens to pressure at high altitudes
pressure will decrease as altitude increases because of the lower density of air at higher places. that’s why mountain climbers need oxygen tanks because there is less air and less dense air.
pressure of different jets of water at the different parts of the container
As depth increases, pressure increases. Water from lowest jet experiences greater force so it emerges with a greater speed and travels further. Water from highest jet experiences lesser force and emerges with lesser speed and hits ground closest to the can.
pressure of different points at the same level
All points at the same level of a fluid experience the same pressure, regardless of shape, size or volume about that point.
application of pressure in gases
suction cups : air sucked out from the cup so it sticks to the wall, becomes partial vacuum, and the atmosphere pressure acts on the outside of the cup to hold it in place. To increase holding power suck out more air from the cup or use a cup with a larger surface area.
application of pressure in liquids
hydraulic press, to convert a small force at input to larger force at output. In a hydraulic car jack.
formula for pressure
p = F/A
pressure equals to forced divided by the contact area
formula of pressure and area in hydraulic press
F1/A2 = F2/A2
force exerted at piston 1 over surface area in piston 1 is equal to force exerted at piston 2 over surface area in piston 2
formula for convertion (N to Kg or vise versa)
W = m g
Weight (N) = mass (Kg) times gravitational filed strength (10N/kg)
