4.5.5 - Pressure and pressure differences in fluids

Question 1

Why does atmospheric pressure decrease with altitude?

Answer 1

• Because there is a lower weight of air above you, the air is less dense at higher altitudes.
• This causes there to be fewer molecules per cubic feet and therefore reduces the number of collisions per second

Question 2

What is the atmosphere?

Answer 2

A thin layer of air around the Earth. The atmosphere gets less dense with increasing altitude.

Question 3

What happens when an object is submerged in water?

Answer 3

The bigger the volume of water is displaced and up thrust increases

Question 4

When does an object float?

Answer 4

When its weight is equal to its upthrust

Question 5

Why does water pressure increase with depth?

Answer 5

Because there is greater weight of water above it

Question 6

Why is the air less dense at higher altitudes?

Answer 6

• At increased altitudes, there is less weight of air above, so atmospheric pressure decreases with increasing altitude

Question 7

When does an object sink?

Answer 7

When its weight is greater than the upthrust

Question 8

Why does an object that is less dense that the liquid float?

Answer 8

Its weight is less than the weight of the liquid it displaces

so the weight of the object is less than the upthrust on the object when it is fully immersed

Question 9

Why does an object that is more dense than the liquid sink?

Answer 9

Its weight is greater than the weight of the liquid displaced..

So the weight of the object is greater than the up thrust on the object when it is fully immersed

Question 10

A fully immersed object displaces:

Answer 10

an equal volume of water as said object