Topic 11 - Force and Pressure Flashcards
What is upthrust?
The upward force that acts on a body partly or completely submerged in a fluid.
What is a Pascal?
A unit of pressure equivalent to one Newton per metre squared.
How does liquid pressure change the deeper you go?
The deeper you go the higher the pressure since the volume of water exerting force from above you is greater.
What is the equation for Pressure?
Pressure = Force/Area
What is the equation for pressure in a liquid?
Pressure = density x gravitational field strength x depth (height) under the surface
What is pressure equal?
The force per unit of area.
How does atmospheric pressure increase with altitude?
Atmospheric pressure decreases since there are less air particles above you at higher altitudes above sea level.
How does water pressure change with depth?
The deeper an object is under water, the higher the pressure since there is a higher volume of water above it and therefore acting on it.
What is the equation for density?
Density = mass/volume
If an object has a lower density than water, will it float or sink?
It will float.
What causes upthrust?
The difference in pressure between the liquid and the object in the liquid causes upthrust.
What happens to pressure as you go deeper underwater?
It increases with depth as there is more water above you
Apart from depth, what else affects pressure in a liquid?
Density
What causes atmospheric pressure?
Molecules colliding with surfaces, exerting a force on the object.
How far does Earth’s atmospheric pressure extend?
Over 100km into space.
How do suction cups relate to atmospheric pressure?
It doesn’t fall off of a wall as the action of pressing it on the wall squeezes air trapped between the. The force due to atmospheric pressure acts on the outside surface and keeps it on the wall.
What happens to atmospheric pressure as you gain altitude?
Pressure decreases
What is the atmosphere?
A thin layer of air around the Earth.
What happens when a ship is loaded with more cargo?
It floats lower. This ship displaces more water so upthrust increases. It may sink if water cannot carry out upthrust as the weight is too high.
When does an object float?
When its weight is equal to the upthrust.
When does an object sink?
When its weight is greater than the upthrust
What is true about objects with greater density than water?
They sink as they weigh more than the liquid they displace
What is true about objects with a lesser density than water?
They float as they weigh less than the water they displace.