Pressure (triple only) Flashcards
Define the term fluid
A substance that can flow a liquid or a gas
State the unit of pressure that is equal to 1 Newton per square metre
Pascal Pa
Explain why the pressure in a liquid increases with depth
Pressure is due to the weight of the liquid and the weight of a liquid depends on its density. As depth increases the weight of the liquid increases.
Define upthrust
The resultant force due to the difference in pressure between the top and bottom surfaces of an object submerged in a fluid
Describe what an object placed in a fluid will do if it’s weight is equal to the upthrust
Float
Describe what an object placed in a fluid will do if it’s weight is greater than the upthrust
Sink
Explain why an object that is more dense than a fluid Sinks if placed in the fluid
The weight of the object is greater than the weight of the fluid displaced so the weight of the object is greater than the Upthrust
Explain why an object that is Less dense than a fluid Floats if placed in the fluid
The weight of the object is Less than the weight of the fluid displaced so the weight of the object is Less than the Upthrust
Does an object that is partially submerged in a fluid experience a greater pressure on its bottom or top surface
Bottom
Describe what the Earth’s atmosphere is
Layer of air that surrounds the Earth
Describe what atmospheric pressure is caused by
Air molecules colliding with surfaces
Explain why atmospheric pressure decreases with increased altitude
The density of air decreases so there are fewer air molecules as you go higher, so fewer collisions with surfaces.
Compare the height of the atmosphere to the radius of the Earth
The height of the atmosphere is smaller than the radius of the Earth
