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0 points1stop10y ago0 comments

... We are talking a tangent on a circle that is changing every second.

So that is a change of velocity, which is acceleration. Outwards is clearly "out" of the circle. The tangent (on the curve) would be a snapshot of that "outward" velocity.

As a said: Tangential velocity is the same as saying outward acceleration. Unless you were referring to just that single "snapshot" in a frozen time scenario.

That "outward" force usually comes from a massive rocket... It is then maintained by the inward force of gravity.

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marcosscriven10y ago

Nothing is accelerating outward. There's only one acceleration here, and that's towards the centre of the mass of Earth.

1stopOP10y ago

If that were the case then you could get into orbit by simply going straight up. Why do they go laterally up to 8km/s then? (if not to generate an 'outward' force?).

There are two vectors being added here. One is gravity. The other is a tangental/outward vector. When added together, they form an orbit. Ignore one, and you leave orbit, either by going into space, or smashing into earth. But there are clearly two forces/vectors. And one of them, is having it's direction changed by the other, and thus is acceleration... I don't know what other words I can use to describe it. But I fail to see where I'm wrong :\

vectorjohn10y ago

The only force, and therefore the only acceleration, when you're in orbit is the force of gravity. And therefore, the only acceleration is towards the center of Earth.

The thing in orbit is already moving with a high enough velocity that it isn't able to get closer to the Earth.

I guess maybe what you're saying, is if you take the velocity vector and apply the acceleration vector over time, that changes the velocity at the same rate as the curve of the Earth.

Either way, there is exactly one force vector (which causes exactly one acceleration vector), not two.

marcosscriven10y ago

Accidentally up voted you :)

They get to that vast 8km/s veloctiy you mention with huge rocket engines. Then they turn them off.

At that point the astronauts and their craft are in freefall.

You mention an outward 'vector'? You can only talk about forces and their effects on masses really. There's an intertia that resists the downward acceleration, but that's not a force.

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simbilou_10y ago

A laughable claim, mister Bond, perpetuated by overzealous teachers of science.

marcosscriven10y ago

:) https://www.explainxkcd.com/wiki/index.php/123:_Centrifugal_...

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marcosscriven10y ago

Nothing is accelerating outward. There's only one acceleration here, and that's towards the centre of the mass of Earth.

1stopOP10y ago

If that were the case then you could get into orbit by simply going straight up. Why do they go laterally up to 8km/s then? (if not to generate an 'outward' force?).

vectorjohn10y ago

The only force, and therefore the only acceleration, when you're in orbit is the force of gravity. And therefore, the only acceleration is towards the center of Earth.

The thing in orbit is already moving with a high enough velocity that it isn't able to get closer to the Earth.

I guess maybe what you're saying, is if you take the velocity vector and apply the acceleration vector over time, that changes the velocity at the same rate as the curve of the Earth.

Either way, there is exactly one force vector (which causes exactly one acceleration vector), not two.

marcosscriven10y ago

Accidentally up voted you :)

They get to that vast 8km/s veloctiy you mention with huge rocket engines. Then they turn them off.

At that point the astronauts and their craft are in freefall.

You mention an outward 'vector'? You can only talk about forces and their effects on masses really. There's an intertia that resists the downward acceleration, but that's not a force.

1 more reply

simbilou_10y ago

A laughable claim, mister Bond, perpetuated by overzealous teachers of science.

marcosscriven10y ago

:) https://www.explainxkcd.com/wiki/index.php/123:_Centrifugal_...

j / k navigate · click thread line to collapse