Topic 5 Upthrust And Atmospheric Oressure Flashcards

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1
Q

What happens when an object is submerged in a fluid

A

The pressure of the fluid exerts a force in it from every direction

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2
Q

Why is the force exerted on the bottom of the object larger than the force exerted in the top

A

Pressure increases with depth

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3
Q

What is upthrust in liquid equal to

A

The weight of the fluid that has been displaced by the object

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4
Q

Why will an object float

A

If the upthrust of an object is equal to the objects weight then the forces balance

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5
Q

When will an object sink

A

If an objects weight is more than the upthrust

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6
Q

What does wether or not an object floats depend on

A

It’s density

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7
Q

Density causing an object to float

A

An object that is less dense than the fluid it is placed in, weighs less than the equivalent volume of the fluid this means that it replaces a volume of fluid that is equal to its weight before it’s completely submerged
therefore the weight is equal to upthrust so it floats

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8
Q

What happens to an object that is denser than the fluid it is placed in

A

Unable to displace enough fluids to equal its weight
This means it’s weight is always larger than it’s upthrust so it will sink

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9
Q

How do submarines rise and sink

A

Make use of upthrust
Large thanks are filled with water to increase weight of submarine so it is more than upthrust and will sink
To rise to the surface, the tanks are filled with compressed air to reduce the weight so it’s less than upthrust 

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10
Q

What is the atmosphere

A

Layer of air that surrounds the Earth and this thin compared to the size of earth

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11
Q

How is atmospheric pressure created on the surface

A

By air molecules colliding with the surface

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12
Q

What happens as altitude increases

A

Atmospheric pressure decreases

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13
Q

What happens as altitude increases

A

The atmosphere gets less dense so there are fewer air molecules that can collide with the surface

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14
Q

What does having fewer air molecules above the surface is height increases mean

A

The weight of the year above it which contributes to atmospheric pressure decreases with altitude

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