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A short class with Sarah and her students. The other ways are under More.
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Today, we're going to explore how the altitude affects the value of gravitational acceleration, or g. Can anyone tell me how g changes as we go higher above the Earth's surface?
I think it decreases as we go higher?
Exactly! g decreases with altitude because we're moving away from the center of the Earth. Remember the phrase 'Higher, less power'? That can help you remember!
So, if I were on top of Mount Everest, I'd weigh less than at sea level?
Correct! The difference might not be huge, but you would weigh a bit less. It's an important factor in fields like aerospace and sports science.
How much does it actually change?
Great question! For every kilometer you go above sea level, g decreases by about 0.3%. It may sound small, but over large distances, it does add up!
That’s cool!
Alright, to summarize: g decreases with altitude, meaning as you rise, your weight slightly decreases too. Remember 'Higher, less power' for future reference!
Now, let’s shift our focus to depth. Who can remind me what happens to gravitational acceleration as we go deeper into the Earth?
It decreases, right?
Yes! But why do you think that happens?
Is it because there's less mass above us?
Absolutely! As you go deeper, the mass of the Earth above you decreases which reduces the gravitational pull acting on you. This is a crucial concept to understand in geophysics.
Does that mean if I dug a hole to the center of the Earth, I wouldn’t feel any gravity?
Exactly right! At the center, you would experience zero g due to equal gravitational forces pulling you in every direction.
That sounds wild!
To wrap it up: gravity decreases as we go deeper into the Earth because of the decreasing mass above you. Think of the saying 'Down below, gravity’s low'!
For our final factor, let’s talk about latitude. Who can explain how gravity changes with latitude?
Isn't it strongest at the poles and weakest at the equator?
That's right! This happens due to Earth's shape and rotation. The phrase 'Pole’s pull, Equator’s lull' can help remember this distinction!
Why does the Earth's shape affect gravity?
Good question! The Earth is not a perfect sphere but an oblate spheroid. This means there’s more distance from the Earth’s center at the equator compared to the poles.
So, does that mean an astronaut closer to the equator will weigh less?
Exactly! The centrifugal force due to rotation at the equator also slightly reduces the effective weight. It’s a fascinating interplay between gravity and rotation!
That’s interesting!
To sum up: g varies with latitude, being maximum at the poles and minimum at the equator. Always think 'Pole's pull, Equator's lull' to remember!
Altitude high, gravity low, deeper down, it starts to slow.
Imagine climbing Everest while feeling lighter, only to realize it’s the altitude. Then diving deep into a mine where gravity feels less because the mass above you is fewer.
A.D.L.: Altitude decreases, Depth decreases, Latitude varies.
G.A.D.L.: Gravitational effects from Altitude, Depth, Latitude.
Term
Effect of Altitude on g
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Term
Effect of Depth on g
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Effect of Latitude on g
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The acceleration experienced by an object due to the force of gravity.
The height of an object above a reference point, typically above sea level.
The distance below a surface, which in this context refers to how far below the Earth's surface one is.
The measurement of distance north or south of the equator, affecting the gravitational force experienced.
The shape of Earth, which is slightly flattened at the poles and bulging at the equator.
The value of gravitational acceleration (g) changes based on altitude, depth, and latitude.
This section discusses three main factors that influence the value of gravitational acceleration: altitude, where g decreases as you rise above Earth’s surface; depth, where g decreases as you move into the Earth; and latitude, where g varies from maximum at the poles to minimum at the equator due to Earth's shape and rotation.
Gravitational acceleration, commonly denoted as g, is not a constant value everywhere on Earth. It is influenced by various factors:
Altitude: As one moves higher above the Earth's surface, such as when climbing a mountain or flying in a plane, the value of g decreases. This is because the distance from the center of the Earth increases, reducing gravitational attraction.
Depth: Conversely, as we delve deeper into the Earth’s crust, g also decreases. This is due to the reduction in the amount of mass above a person, which partially cancels out the gravitational force pulling them down.
Latitude: The value of g varies across different latitudes on Earth. It is highest at the poles and lowest at the equator. This discrepancy arises from Earth's oblate spheroid shape and its rotation, which causes the equatorial region to bulge outward. The resultant inertia due to Earth's rotation at the equator further diminishes the gravitational pull experienced.
Understanding these factors is crucial for various scientific and engineering applications, from satellite launches to building structures and ensuring safety in high-altitude activities.