Sec 9.1 Flashcards
Atmosphere?
A layer of gases that surround a body, like a planet or a moon, that is retained by the body’s gravity
What is the practical boundary of earths atmosphere?
100-120km ,though it does extend for thousands of km
What r the 5 main layers
Troposphere 0-12km Stratosphere 12-50km Mesosphere 50-85km Thermosphere 85-650km Exosphere 650-10000km
Atmospheric pressure?
Pressure due to gravity pulling down on all the atmosphere above the object
The higher the altitude, is it the less air is pushing down on you or the more?
Less
What does less air above you mean?
Less mass
What does less mass mean?
Less force
What does less force mean ?
Less pressure
What do fluids naturally do?
Fluids naturally flow from area of high pressure to areas of low pressure
If a gas is sealed inside a closed container at a lower pressure and the pressure outside the container, what is the pressure difference?
The pressure distance creates an unbalanced force
What happens if the container is strong enough?
Nothing changes
What happens if the container is not strong enough?
The container will crush inwards
What pressure are you feeling when your underwater?
The pressure you feel is the result of the weight of water above you
Does the pressure increase or decrease with depth?
Increase
101.3 kpa is how many atmosphere ?
One or 1atm
What is atmosphere unit?
A unit for pressure, mainly use for atmospheric pressure, equal to 101.3 kpa or sealevel
In water for each 1atm how many Metres of depth?
10m of depth
1atm is approximately how many newtons?
100 000newtons
Buoyancy?
The tendency of objects in fluids to rise or sink depending on differences between there density and the density of the fluid
Objects that have negative buoyancy…
Will sink
Objects that have positive buoyancy…
Will rise
Objects that have neutral buoyancy…
Will remain stabile
Buoyant force?
Th upward force exerted by a fluid
What does the buoyant force depend on?
Fluids density
What happens to the buoyant force when the density increases?
Buoyant force increases
What does the object rise of sink depends on?
Depends in the balance between the force of gravity pulling the object down and the buoyant force pushing it up
When the force of gravity is pulling down and the buoyant force is pushing up, what happens?
The object neither rises or sinks
The forces are equal in strength, but in opposite direction
What happens when the object sinks?
The strength of gravitys downward pull on the objects depends on its mass (or its densities ->the more dense means more mass)
What is the earth surrounded by?
Atmosphere
What does more dense mean?
A stronger force of gravity
What happens if the object rises?
The strength of gravity downwards pull on the object depends on its mass ( or its density-> more dense equals more mass)
What does less mass mean
A weaker force of gravity
Fluids also rise and fall due to changes in..
Densities
Thermal expansion lead to higher or lower density
Thermal expansion..increase in temperature…increase in volume..decrease in density
Thermal contraction lead to higher or lower density
Thermal contraction…decrease in temperature..decrease in volume..increase in density
What happens when a fluid warms
Expands and becomes less dense
What does less dense mean?
Weaker pull of gravity
What does weaker gravitational pull mean?
Fluid will rise
What happens when a fluid cools
Contracts and becomes more dense
What does more dense mean
Stronger pull of gravity
What does stronger gravitational pull mean?
Fluid will sink
Convection?
A vertical movement (rising or falling) of fluid because of a change in its density, usually because of a change in there temperatures
