# Pressure ✔

Flashcards by Farha Idrees, updated more than 1 year ago
 Created by Farha Idrees about 4 years ago
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Pressure

## Resource summary

 Question Answer True or False? Pressure is a force. False. Pressure is not a force. What is pressure? The force exerted over an area. The greater pressure, the greater the force exerted over an area. Give an example of pressure in real life. -Hitting a nail: the sharp point of the nail concentrates the force over a very small area so the nail can move through the wall -Vehicles with caterpillar tracks: lets them spread their weight over a larger area so it does not sink -Sharks with sharp teeth: sharks can then concentrate all the force from their jaw into the small area at the tip of their teeth- this allows them to tear flesh What needs a high pressure? -Nail -Drill bit -Screw -Ice skates -Sewing needle -Bread knife What needs a low pressure? -Tractor tires -Aeroplane wings -Building foundations -Snow shoes -Camel's feet What is pressure measured in? Pressure is measured in N/cm² or N/m². How do you work out pressure? Pressure= force/ area Area= force/ pressure Force= area* pressure What are pascals? These are also units of pressure. 1 Pa is the same as N/cm². What is the pressure on the floor when a man of weight 750 N stands on the area of 250 cm²? pressure = force/area = 750/250 = 3N/cm² The weight of a man is 900 N. The pressure upon the floor is 4 N/cm². What is the area of his shoes? area = force/pressure = 900/4 = 225 cm² Is there air pressure in space? There is no air pressure in space. What is atmospheric pressure? the weight of the air resting on Earth's surface Complete these sentences: -The ____ particles there are in one space, the higher the ______ -The more ________ there are, the greater the pressure is -The more _____ there is in the collision, the ______ the pressure -The _____ the area the collisions affect, the greater the ______ is -The more particles there are on one space, the higher the pressure -The more collisions there are, the greater the pressure -The more force there is in the collision, the higher the pressure -The smaller the area the collisions affect, the greater the pressure is What happens when you compress a gas? Compressing a gas increases the pressure as the particles now occupy a smaller space Can liquids be compressed? Liquids cannot be compressed or squashed as the particles are packed more closely together than they are in gases with very little space in between them. Why does the pressure increase with depth in water? The pressure increases with depth because the deeper you go the greater the weight of water pushing downwards. Fill in the gaps: -pressure at any ___ depth is always the _____ -the ________ increases as the depth ________ -the pressure acts in ___ ________ -pressure at any one depth is always the same -the pressure increases as the depth increases -the pressure acts in all directions What are hydraulics? Systems or machines that are designed to transmit forces through liquids are called hydraulic machines Why do hydraulic machines work? As liquids cannot be compressed and the pressure in them acts in all directions, they can be used to transmit forces from one place to another. The basic idea is very simple- the force that is applied at one place is transmitted by the fluid to another place. How does a hydraulic machine work? (5) 1. The force is applied to Piston 1, which moves down. 2. The piston exerts a pressure on the fluid in the cylinder 3. This moves a volume of fluid under the piston. 4. The pressure is the same throughout the fluid so the moved fluid moves through the tube to the other cylinder. 5. As it moves in, the pressure in the fluid exerts a force on Piston 2, which moves up. This is a diagram of a hydraulic machine: 41c054fb-1fed-415b-80c0-2d621faee0a8.gif (image/gif) Here is an animation of a hydraulic machine: https://www.youtube.com/watch?v=pEH3faVI6j0

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