Pressure

Question 1

What is pressure

Answer 1

• Fluids (either gas or liquids) are substances that can flow because their particles are able to move around .
• As these particles move around they collide with surfaces within the object. They exert a force on the object they collide with .
• This force is called pressure
• The pressure act at a right angle to the object it collides to

Question 2

What is the equation for pressure

Answer 2

Pressure (pascals)= force(N) / area(m^2)

Question 3

Why does pressure increase with density

Answer 3

The more dense a liquid is the number of particles it has increases . This means that there are more particles able to collide so pressure is higher

Question 4

Why does pressure increase with depth

Answer 4

-As depth increases so does the amount of particles above that point. The weight of these particles adds to the pressure felt at that point . So liquid pressure increases with depth

Question 5

What is the equation to work out pressure in a liquid

Answer 5

Pressure=height of column of the liquid ( the depth)(m)x gravitational field strength x density of the liquid

Question 6

Why do objects in fluids experience upthrust

Answer 6

• When an object is submerged in a fluid the pressure of the fluid exerts a force on it from every direction
• Pressure increases with depth so the force exerted on the bottom of the object is bigger than that acting on the top of the object
• This causes a resultant force upwards known as upthrust
• This upthrust is equal to the wieght of the fluid that has been displaced

Question 7

How does density effect if an object floats or sinks

Answer 7

• An object floats if its weight is equal to its upthrust
• an object that is less dense than the fluid it is placed in weighs less than the equivalent volume of fluid. This means it can displace a volume of fluid equal to its weight before it is completely submerged and its upthrist can equal its weight making it float.
• An object that is denser than its fluid is unable to displace enough fluid to equal its weight. This means Its weight is always larger than upthrust so it sinks

Question 8

What is the atmosphere

Answer 8

The atmosphere is a thin layer of air around the earth which becomes less dense with increasing altitude

Question 9

How is atmospheric pressure created

Answer 9

Atmospheric pressure is created on the earths surface by particles colliding with the surface

Question 10

Why does atmospheric pressure vary with altitude

Answer 10

• As altitude increases atmospheric pressure decreases
• This is because as altitude increases the atmosphere gets less dense meaning there are less particles to collide with the surface
• There are also fewer air molecules above a surface(e,g mountains ) as altitude increases . This means that the weight of air above the surface,which contributes to atmospheric pressure, decreases with altitude