P1.3 Pressure

Question 1

What is gas pressure?

Answer 1

The forces produced from collisions of particles with the inside of a container

Question 2

When is pressure exerted?

Answer 2

When you add more particles to a container that cannot expand or when you decrease the volume of the container

Question 3

How does temperature affect gas pressure?

Answer 3

As the temperature of gas particles increase, the particles gain more kinetic energy so they collide more frequently and with more force with the side of a container. This produces a bigger pressure

Question 4

How is pressure measured?

Answer 4

Using a pressure gauge. Measured in Pascals

Use formula: pressure(pa)=force(n)/area(m2)

Question 5

What is the relationship between pressure and temperature?

Answer 5

As temperature increases, so does pressure. It is directly proportional

Question 6

What is the relationship between pressure and volume?

Answer 6

As volume doubles pressure halves and as volume halves pressure doubles. The relationship is inversely proportional so pressure = 1/volume

Question 7

Why does pressure decrease as volume increases?

Answer 7

The collisions of gas particles at a normal to the surface create a force. Halving the volume decreases the space in the container which increases the frequency of collisions per second.

Question 8

Calculating pressure and volume

Answer 8

Pressure(pa) x volume(m3) = constant

Question 9

Why does a bicycle pump get hot when you pump?

Answer 9

A force is applied over a distance which means that work is done. The kinetic energy increases because they collide faster.

Question 10

What is the atmosphere?

Answer 10

A layer of gas that covers the surface of the earth to protect it for about 700km. It is assumed that density is the same at all parts

Question 11

What is atmospheric pressure?

Answer 11

The pressure exerted by gases in the atmosphere. It is 101kPa or 101000 Pa

Question 12

What is the relationship between atmospheric pressure and altitude?

Answer 12

As altitude increases atmospheric pressure decreases. This is because the higher you go the less particles there are pushing down on you

Question 13

Why do crisps packets expand when you go on airplanes?

Answer 13

Air pressure outside the crisp packet is lower than inside. This means that the forces on the surface of the packet are uneven which means that it will push out

Question 14

Explain why Felix had to wear a specialised pressure suit during his dive

Answer 14

At lower pressures, liquids boil at lower temperatures so a suit is needed to maintain the pressure on his body to stop his blood from boiling.

Question 15

What is another equation for pressure and volume?

Answer 15

P1XV1 = P2 X V2

Question 16

What is liquid pressure?

Answer 16

The force exerted by liquids on the container and any other particles

Question 17

What is the relationship between liquid pressure and depth?

Answer 17

The lower you go the more particles are pressing down from up. The denser the liquid, the more particles pushing down there are as well.

Question 18

Calculating liquid pressure

Answer 18

Pressure(pa) = height of column(m) x density(kg/m3) x gravity(n/kg(10))

Question 19

Explain the bottle experiment

Answer 19

The lower you go on the the bottle, the further the the water goes. This is because the lower you go, the more pressure there is so it goes further

Question 20

Why do bubbles from a diver expand as you go up?

Answer 20

As you go up, water pressure decreases which means that there is less pressure on the bubble which allows them to expand

Question 21

Why is there an upwards force on a floating object?

Answer 21

When an object is in contact with water the water has a bigger upwards force than the air has a downwards force so the net force is upwards. This is upthrust.

Question 22

What factors influence whether an object floats or sinks?

Answer 22

Weight and area. Increasing the weight decreases the upwards force, which means if a submarine takes on more water it will sink and if it releases water it will float.

This is also how fish adjust depth: varying the amount of gas in them

Question 23

Formula for pressure and area

Answer 23

Pressure(pa) x area (m2) at bottom = weight(kg) + pressure x area a top