P1.3 Pressure Flashcards
Why do gases exert pressure?
Gases within a container collide with the inside surface. Each collision produces a small force and the many collisions produce an outward force. This is gas pressure
How does temperature affect pressure?
If the temperature of gas increases, gas particles have higher kinetic energy and move faster. They collide more frequently with the side of the container. The more collisions produce a greater force over a certain area. This produces a greater pressure.
What is the pressure formula?
Pressure = Formula /// Given Area
How & Why are pressure and volume related?
Pressure and volume are inversely proportional.
As volume doubles, the pressure halves
As volume halves, the pressure doubles
If volumes changes, the space for particles changes and so the number of collisions change influencing pressure
What is pressure and volume formula
Pressure (Pa) X Volume (m3) = Constant
What is atmospheric pressure?
The gases in the atmosphere exert a pressure called atmospheric pressure.
On the surface of the Earth atmospheric pressure is 100 kPa.
What happens to atmospheric pressure as you go up?
As you go away from the surface of the Earth, the atmospheric pressure decreases. This is because there is less air above pushing down as gravity is bringing more air to Earth’s surface.
What is liquid pressure?
The water exerts a liquid pressure. This is because water molecules are very close together and they collide with each other. Liquid pressure acts in all directions
What happens to liquid pressure as you go deeper?
As you go deeper, there is a greater pressure. Molecules in a liquid are being compressed by the weight of all the liquid above that layer. This pushes water molecules together so pressure is bigger
How do you calculate liquid pressure?
Pressure (Pa) = Height of column (m) X Density of liquid (kg/m3) X Gravitational field strength (N/kg)
Why is there an upwards force on a floating object?
Anything that is floating must have an upwards force on it to balance its weight. In the upthrust, the water exerts a bigger upwards force on you that the downwards force exerted by the air. The net force is upwards
What formula dictates whether an object floats?
The net force depends on the difference in pressure and on the area.
(Pressure at bottom X Area) - (Pressure at top X Area) = Weight
Why do some objects float and others sink?
It all depends on the resultant force caused by the weight of the object and the upthrust.
