11

Question 1

what is pressure caused by

Answer 1

when 2 objects exert a force on each other or when a fluid exerts a force on an object in contact with the fluid.

Question 2

why do caterpillar tracks on vehicles help them in sandy/muddy/snow ground

Answer 2

they spread the weight of the vehicle reducing the pressure

Question 3

pressure definition

Answer 3

force per unit area

Question 4

pressure unit

Answer 4

pascal (Pa)

Question 5

what is one pascal equal to

Answer 5

one newton per square metre (N/m3)

Question 6

pressure equation

Answer 6

pressure = force/area

Question 7

why does a sharp knife have a bugger cutting effect than a blunt one (same force)

Answer 7

It has a smaller area which means there is a bigger pressure

Question 8

what happens to pressure of water with depth

Answer 8

increases

Question 9

what does the pressure of a liquid depend on

Answer 9

density

Question 10

what does a greater density of liquid mean

Answer 10

greater pressure

Question 11

In a liquid what must the pressure be a horizonal points

Answer 11

equal

Question 12

explain this

Answer 12

Oil is less dense that water, this means it will create a lower pressure. Since the pressure at horizonal points X and Y must be equal, there needs to be more oil to create an equal pressure.

Question 13

what is the equation for the pressure at the bottom of a column of liquid

Answer 13

pressure=heightdensitygravitational potential field strength

Question 14

what does the atmosphere do to the earth , and give a number for this

Answer 14

exerts a pressure on it. 100,000N at sea level

Question 15

what is atmospheric pressure due to

Answer 15

air molecules colliding with surfaces

Question 16

what happens to the density of the atmosphere with increasing height

Answer 16

decreases

Question 17

what determines density of air

Answer 17

the weight of the air above a given point pushing down, compressing the air below.

Question 18

why does density decrease with higher altitude

Answer 18

As you go higher there is less air above, so there is less weight of air pressing down. This means particles are not compressed, making it less dense.

Question 19

why does a suction cup work

Answer 19

it removes the air between the cup and the wall. This means that that atmospheric pressure acts on the outside of the cup but not the inside. Making it stick to the wall.

Question 20

why does a straw work

Answer 20

when you suck you remove air above the liquid, without any atmospheric above the liquid, the pressure acting on the liquid outside the straw pushes it up.

Question 21

what happens to oxygen concentration with increasing altitude

Answer 21

decreases

Question 22

what force does water exert on the body

Answer 22

upthrust

Question 23

why does the water level rise when an object is lowered into a container

Answer 23

the object displaces water

Question 24

what happens the more an object is lowered into water

Answer 24

the bigger the volume of water it displaces and the bigger the upthrust

Question 25

what happens when an object is fully immersed in water

Answer 25

volume of water displaces is equal to the volume of the object

Question 26

why is upthrust greater than the downward force of an object immersed in water

Answer 26

pressure is greater with greater depth of water, so pressure at the bottom of the object is higher

Question 27

what does a ship do to water when its load is increased, and what is this effect

Answer 27

it displaces more, it increases the upthrust

Question 28

what causes a ship to sink when being loaded

Answer 28

it has displaced as much water as it possibly can, and the upthrust is now lower than the weight

Question 29

when does an object float

Answer 29

when its weight is equal to the upthrust

Question 30

when does an object sink

Answer 30

when its weight is greater than the upthrust

Question 31

what is the density of objects that float

Answer 31

less than water

Question 32

what is the density of objects that sink

Answer 32

greater then water

Question 33

what is upthrust equal to

Answer 33

weight of liquid displaced

Question 34

why does an object that is more dense than liquid sink

Answer 34

because its weight is greater than the weight of liquid displaced. So the weight of the object is greater than the upthrust on the object when it is fully immersed.

Question 35

why does an object less dense than the liquid float

Answer 35

its weight is less than the weight of liquid it displaces. So the weight of the object is less than the upthrust on the object when it is fully immersed.