Flashcards
What is gas pressure?
The force exerted over a certain area by a gas, measured in Newtons per metre squared (N/m²)
Gas pressure is due to the collisions of gas molecules with surfaces.
What causes atmospheric pressure?
The collisions of air molecules that produce a force on an area
Atmospheric pressure decreases with altitude.
How is density defined?
The mass of a material in a certain volume, measured in grams per metre cubed (g/m³)
Density is a key factor in determining whether an object will float or sink.
What is liquid pressure?
The pressure produced by collisions of particles in a liquid
Liquid pressure increases with depth.
What does pressure measure?
The force exerted on a given area, measured in Newtons per metre squared (N/m²)
Pressure acts in every direction in a fluid.
What defines a fluid?
A substance with no fixed shape, a gas or a liquid
Fluids can flow and take the shape of their container.
What is upthrust?
The upward force that a liquid or gas exerts on a body floating in it
Upthrust is also known as buoyant force.
How does pressure act in a fluid?
Pressure acts in every direction
This omnidirectional pressure is why we do not feel it despite its presence.
Why is liquid pressure greater than air pressure?
In any volume of a liquid, there are vastly more particles compared to in air, so there is a greater pressure
This is due to the density and incompressibility of liquids.
What happens to pressure as you go deeper in water?
The pressure arrows get bigger, indicating a larger pressure
This increase is due to the weight of the water above.
What is the formula to calculate pressure?
Pressure = Force ÷ Area
This formula allows for the calculation of pressure in various scenarios.
Calculate the pressure if a force of 20 N acts over an area of 4 m².
5 N/m²
This pressure can also be expressed as 5 Pa (pascals).
What is 1 Pascal (Pa) in terms of Newtons per square metre?
1 Pa = 1 N/m²
The pascal is the SI unit of pressure.
What happens to gas pressure when the volume of the gas is reduced?
The gas pressure increases
This is due to more collisions between gas molecules and the walls of the container.
Where is atmospheric pressure greater?
Closer to the surface of the Earth
This is due to the weight of the air above exerting pressure.
Why are liquids considered incompressible?
Particles in a liquid are touching, so they cannot be squashed closer together
This property allows liquids to transmit pressure uniformly.
When do objects float?
When the upthrust from the liquid is big enough to balance the force from their weight
This principle is defined by Archimedes’ principle.
What is the relationship between upthrust and the weight of the fluid displaced?
Upthrust = weight of the fluid displaced by the object
This relationship is crucial for understanding buoyancy and floating.
What is a force?
A push or pull. The unit of force is the newton.
What is friction?
A contact force between two surfaces in the opposite direction to motion.
What is air resistance?
A force of friction produced when an object moves through the air.
What is water resistance?
A force of friction produced when an object moves through liquid.
What is tension?
Pulling force exerted by each end of an object such as a string or rope.
What is weight?
The force acting on an object due to the pull of gravity from a massive object like a planet.
What is upthrust?
Upwards force exerted by a liquid or gas on an object floating in it.
What is a reaction force?
Force exerted in the opposite direction to an action force.
What is the formula for volume of regular shapes?
V = L x W x H.
How do you find the volume of irregular shapes?
Immerse the object in a displacement can and find the volume of water/object using a measuring cylinder.
What do balanced forces indicate?
Balanced forces = no acceleration.
What happens when a resultant force is exerted on an object?
It can change the object’s speed, direction of movement, and/or shape.
How can drag through a fluid be reduced?
By streamlining.
What do elastic materials do when force is removed?
They return to original shape.
What can forces do to the shape of objects?
Forces can change the shape of objects by stretching or compressing.
What does Hooke’s law state?
The extension of a spring doubles when the force doubles.
What happens when the elastic limit is exceeded?
The material will not return to its original shape.
What is the formula for density?
Density = mass/volume.
What is the condition for equilibrium in moments?
Sum of clockwise moments = sum of anti-clockwise moments.
