P11

Question 1

Fluids are

Answer 1

Substances that can flow because their particles are able to move around

Question 2

Thr pressure of a fluid means

Answer 2

A force is exerted normal (at right angles) to any surface in contact with the fluid

Question 3

Pressure =

Answer 3

Pressure (pascals) = Force normal to a surface (N).
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Area of that surface (m2)

Question 4

Density is

Answer 4

How close together the particles are together

Question 5

Liquid pressure increases with depth because

Answer 5

The number of particles above that point increases. The weight of these particles adds to the pressure felt at that point.

Question 6

Pressure (Pa) =

Answer 6

Height of column of liquid (m) x density of liqiid (kg/m3) x Grav field strength

Question 7

Explain how objects experience upthrust in water…………………….……………”……”…………………………………………………………………………………………………………………………………………………………..

Answer 7

• when object is submerged (partially or completely), the pressure of the fluid exerts force on it from every direction
• pressure increases with depth, so the force exerted on the bottom of object is larger than the force acting on top of the object.
• this causes a resulstant force upwards, (upthrust)
• the upthrust is equal to the weight pf fluid that has been displaced by the object

Question 8

Explain how an object floats/ or doesn’t……..………………

Answer 8

• if the upthrust on an object is equal to the object’s weight, then the forces balance and the object floats.
• if objects weight is more than upthrust, object sinks.
• whether or not an object will float depends on its density.
• an object that is less dense than the fluid it is placed in weighs less than the equivalent volume of fluid.
• meaning it displaces a volume of fluid equal to its weight before it is completely submerged.
• at this point, objects weight is equal to upthrust, so floats.
• anobject that is denser than the fluid it is placed in is unable to displace enough fluid to equal its weight. Mwaning that its weight is always larger than the upthrust so sinks

Question 9

Describe atmospheric pressure

Answer 9

-Atmosphere is layer of air around earth.
- atmospheric prssure is created on a surface by air molecules colliding with the surface.
- as the altitude increases, atmospheric pressure decreases.
- this is because as altitude increases, atmosphere gets less dense, so there are fewer air molecules that are able to collide with the surface.
- there are also fewer air molecules above a surfsce as the height increases.
- meaning that the weight of the air above it, which contributes to atmospheric pressure, decreases with altitude.

Question 10

Atmospheric preseure decreases or increases with height

Answer 10

Decreases with height