Topic 7

Question 1

What is pressure

Answer 1

Pressure- the force acting perpendicular to a certain surface area
2 factors- Force, Area

Question 2

Pascals

Answer 2

Pascal or Pa is a unit of pressure
1pa= 1N/m2
Measured in kPa= 1000 Pa

Question 3

Formula for pressure

Answer 3

Pressure = Force/ Area

P=F/A

Question 4

Requirements for Gas compression

Answer 4

1. The gas must be enclosed in a sealed container with sturdy walls. Gas molecules distribute themselves equally throughout their containers
2. There is so much space between the particles that, even after the particles are squeezed closer together, they are still far enough apart to behave as a gas
3. An external, or outside, force is applied to the enclosed gas, to push the particles closer together

Question 5

Why aren’t liquids and solids compressible?

Answer 5

1. The particles cannot move much closer together.
   Instead the force is transmitted from particles to particle throughout the substance( like dominoes)
   They are called incompressible.

Question 6

Pressure factors

Answer 6

Force, Area, Temp
Increase temp = increase pressure
Increase force = increase pressure
Increase Area = decrease pressure

Question 7

Advantages of Compression

Answer 7

They exert a force back when they are compressed. This creates a cushion shock. Force down means it exerts a force back up.
eg: shoes, air bags, tires

Question 8

Atmospheric pressure

Answer 8

Earths atmosphere is 160 km thick
Earths air is always pushing against us, we don’t feel it because we exert force back
Airn pushes in all direction.
As you get higher up, there are less particles and less pressure. Your bodies doesn’t change as quickly and your ears can pop

Question 9

Measuring Air pressure

Answer 9

Most common device is a barometer
First a thin, strong walled tube , sealed at one end is filled with mercury. Then inverted into a pull of mercury, allowing no air to enter. Mercury fall down the tube, leaving a vacuum( no air) at the top of the tube. As air pushes down on the mercury pool, the mercury is forced up the tube, as the mercury pushes down through the tube and into the pool. The mercury will stop moving when the air pressure equalizes with the force of gravity
Air pressure only supports 760mm of mercury at sea level.

Question 10

Balanced and Unbalanced Forces

Answer 10

If a closed container experiences a lower air pressure than the air pressure pushing on the outside, the walls of the container will buckle and cave in. This creates unbalanced forces. The force of the atmospheric pressure pushes the walls toward the inside of the conatainer.