Solids Liquids And Gasses

Question 1

Why can balloons fly

Answer 1

Gas inside has a low density

Question 2

How do skis work

Answer 2

Spread the weight over the skier over the snow reducing pressure and the skier does not sink into the snow

Question 3

How do solids liquids and gases differ in density

Answer 3

Solids are very dense , liquids less dense , gases low density

Question 4

What is the equation for density

Answer 4

Kg/m3 = mass in kg
———–
Volume in m3
Or g/ cm3

Question 5

How do you find the density of a regular shape

Answer 5

Measure the objects mass on a top pan balance and then calculate volume by mesuring length , width and height with a rule

Question 6

How do you find the density of an irregular solid

Answer 6

1) displacement method have a known volume of water in a measuring cylinder then put an object on a string inside the mesuring cylinder , the water will rise and the amount the water has risen by is the volume
2) eureka can - this method is useful if the object is too big for a measuring cylinder . Fill the eureka can with water to spout and put object in on a string collect the displaced water In a cylinder and measure it

Question 7

Why can you push a pin into Wood but not your thumb

Answer 7

Pin has a small area so the force acting over a small area gives a lather pressure , the same case with a sharp knife and a blunt knife sharp knife is easier because it’s area is smaller

Question 8

What is the equation for pressure

Answer 8

Area in square metres

Question 9

Where does pressure in liquid act

Answer 9

In all directions and it’s transmitted throughout the liquid this is why If you poke holes in a plastic bag filled with water and squeeze it water will come out of all the holes

Question 10

Why would water squirt out fastest at the bottom hole if you filled a can with water and drilled 3 equal sized holes on the side

Answer 10

Beacuse pressure increases with depth

Question 11

Why do tractors need low pressure

Answer 11

Have large tires to spread the vehicles weight reduce the pressure which makes the vehicle less likely to sink into the mud .

Question 12

What is the equation for pressure in a Liquid

Answer 12

Pressure = 10 x depth (m) x density ( kg/m3)

Question 13

How do hydraulic machines work

Answer 13

They magnify forces .2 pistons have the same pressure , piston a has a small force and a small area , if you push on piston a the pressure is transmitted in the liquid to piston b where it makes a larger force as piston b has a large area . This magnifies the force

Question 14

What are hydraulic disc brakes

Answer 14

Used in a car to apply equal forces to all four wheels and to magnify the force on the break . Drivers foot pushes the small piston to exert pressure on the liquid . Pressure is exerted everywhere in the liquid . It’s transmitted to large pistons on echa side of a large disc. The pressure exerts a large force on the large pistons so they squeeze the disc and slow down the car. If the pistons had twice the area of the master piston they will exert twice the force the driver applies with her foot . The force is magnified by the increased area of the pistons

Question 15

What is atmospheric pressure

Answer 15

100 000 pascals

Question 16

Why do we not get crushed by atmospheric pressure

Answer 16

Because the pressure inside our bodies equals atmospheric pressure but if you removed pressure from our bodies the pressure from the atmosphere would crush us

Question 17

How does a mercury barometer work

Answer 17

Mercury barometer can be made by filling a long glass tube with mercury and turning it upside down in a bowl of mercury , it’s held up by air pressure as the air pressure varies the height of the mercury varies a height of 760 mm is standard atmospheric pressure

Question 18

How can you measure gas presssure

Answer 18

By finding the mass of an empty G balloon and then the blowing up the balloon and finding te new mass. Displacement method in a bucket of water to find the volume

Question 19

How does pressure in air change

Answer 19

Acts in all directions becomes less as you rise up through it because there is less weight above . Unlike a liquid air can be compressed which makes the atmosphere denser at lower levels .

Question 20

How does a vacuum cleaner work

Answer 20

A fan lowers the pressure just beyond the bag so the atmosphere rushes in moving from an area of high pressure to low pressure bringing the dust and dirt with it

Question 21

How does sucking on a straw work

Answer 21

Lowers the air pressure at the top of the straw so liquid moves up from an area of high pressure to low pressure

Question 22

What would rain clouds do to a barometer

Answer 22

Cause a lower reading as they form in ares of low pressure

Question 23

What does 1 ATM mean in pascal

Answer 23

100 000

Question 24

What happens in a real hydraulic jack

Answer 24

Friction reduces the output force

Question 25

What are solids like

Answer 25

Definite Rigid shape very dense particles very tightly packed regular arrangement . Strong forces between particles vibrate in a fixed position . When heated vibrate quicker causing an increase in kinetic energy and therefore temperature

Question 26

What are liquids like

Answer 26

Tightly packed particles no definite shape will occupy lowest part of any container, more dense than gases not held in fixed positions but particles are still bound by string forces between then they can move PAst each other and move randomly

Question 27

What are gas like

Answer 27

Very spread out , large spaces between them , small forces holding them together , low density no defenite shape weak forces between particles . Can be compressed move randomnly all the time , they bump into things and the forces caused by the collisions are responsible for the pressures gas exerts . Solids and liquid are harder to compress as the particles between them are very close

Question 28

What is the evidence for continual motion of particles in liquids and gases

Answer 28

Brownian motion - particles of a liquid and gas move around continually and bump into each other and smaller particles, sometimes there will be more collisions on one side of a particle which will make the particle change direction or speed of movement

Question 29

What is boyles law

Answer 29

P1 x V1 = P2 x V2 | Only works if temperature is constant

Question 30

What happens when you compress a gas and why

Answer 30

If you squash a gas into a smaller container it presses on the walls of the container with greater pressure .if the gas is at the same temperature average speed of particles stays the same so if the same number of particles is squeezed into a smaller container they will hit the container walls more often . Each collusion exerts a force on the wall , the more collisions on the wall means greater average force and therefore greater pressure

Question 31

How do you do an experiment to see temperatures effect on pressure

Answer 31

Use a pressure gauge , bulb of trapped air in a water bath and a thermometer to measure temperature

Question 32

What happens to pressure as temperature increases in the gas

Answer 32

It increases , if you cool the gas it decreases but the pressure can't become less than zero which means there is a temperature where u can not cool the gas further this is absolute zero , -273 degreees cejcius

Question 33

How do you convert from kelvin to Celsius

Answer 33

Temperature in K = temperature in Celsius + 273 | Temperature in c = temperature in kelvin - 273

Question 34

What is the equation for the temperature of a fixed mass of gas at a constant volume

Answer 34

``` P1 --- T1 = P2 ----- T2 Temp must be in kelvin ```

Question 35

Why is their a relationship between pressure and temperature in a gas

Answer 35

Because the number of gas particles and the space they occupy remains constant so when we heat the gas the particles continue to move randomly but with a higher average speed . This means collisions with the walls of the container are harder and happen more often increasing average pressure . As we cool the gas kinetic energy of particle decreases so they move more slowly at absolute zero particles have no movement energy so can't exert a pressure

Question 36

What is boyles law based on

Answer 36

PV = constant | Pressure and volume are inversely proportional

Question 37

What happens to a bubble as it rises from the bottom of a lake

Answer 37

Pressure decreases and volume increases

Question 38

What's apparatus would you use to see the relationship between pressure and volume

Answer 38

Oil reservoir , scale to measure the volume and a foot pump to Decrase the volume .pressure gauge to measure pressure

Question 39

How can a manometer be used

Answer 39

Measures pressure difference . Height difference between liquid on each side of the tube shows the extra pressure te gas supply has in addition to atmospheric pressure add atmospheric pressure to excess pressure to find the actual pressure of the gas supply