P11 - Pressure

Question 1

pressure

Answer 1

-caused when object exert forces on each other
-when a fluid exerts a force on an object that it is in contact with

Question 2

fluid

Answer 2

-either liquid or gas

Question 3

pressure depends on

Answer 3

-area of contact
-size of force

Question 4

pressure unit

Answer 4

force per unit area
pascal = n/m^2

Question 5

formula for pressure

Answer 5

p = f/a

Question 6

force must be

Answer 6

90 degrees to surface

Question 7

liquid pressure and depth

Answer 7

-increases with depth

Question 8

water jets in water bottle

Answer 8

-deepest hole = most pressure

Question 9

pressure and density

Answer 9

-higher density = higher pressure in liquids

Question 10

pressure of liquid formula

Answer 10

pressure = h x density x gravity

Question 11

Earths atmosphere pressure

Answer 11

100kPa

Question 12

atmospheric pressure

Answer 12

-due to air molecules colliding with surfaces
-each impact exerts a small force on a surface
-number of molecules that collide each second is large

Question 13

density of atmosphere (altitude)

Answer 13

-decreases as height increases

Question 14

reason for lower air density at higher altitudes

Answer 14

-weight of air molecules above is less
-fewer molecules per cubic metre
-fewer impacts per second

Question 15

pressure at high altitudes

Answer 15

-weight of air above exerts less pressure on air below
-lower pressure

Question 16

Rubber suction cap example

Answer 16

-atmospheric pressure acts on outside of cap only
-forces cap onto wall = forces air out inside
-pressure diff keeps cap onto wall

Question 17

o2 concentration at high altitudes

Answer 17

decreases

Question 18

force from pressure diff formula

Answer 18

pressure difference x area

Question 19

upthrust

Answer 19

upward force on an object due to fluid
-caused by pressure of fluid

Question 20

upthrust in water

Answer 20

water exerts upward force on body it is in contact with

Question 21

adding an object into a body of water

Answer 21

-water level rises
-displaces some water molecules

Question 22

the more the object is lowered

Answer 22

more volume of water is displaced = larger upthrust

Question 23

a fully immersed object’s volume

Answer 23

total water displaced = volume of object

Question 24

upthrust formula of an object that is fully immersed

Answer 24

resultant = pressure below object - pressure above object

Question 25

Ship upthrust example - increasing weight

Answer 25

-load increases = more weight
-displaces more = upthrust increases

Question 26

if upthrust = weight of an object

Answer 26

floats

Question 27

when do objects sink

Answer 27

-when an object displaces max amount of water as water molecules can no longer move and upthrust cannot support its weight

Question 28

if upthrust is less than weight of an object

Answer 28

sinks

Question 29

size of upthrust

Answer 29

= weight of water displaced

Question 30

why will a more dense object sink

Answer 30

-weight is greater than water displaced
-weight > upthrust

Question 31

less dense objects will

Answer 31

float
-displaces less than its weight
-upthrust is enough

Question 32

weight of object is equal to 2 factors

Answer 32

-water displaced
-upthrust