# Questions tagged [velocity]

Questions about the distance objects or gases cover in a fixed amount of time while traveling in space, being launched or descending. Also for questions about speed-comparisons.

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### What is the velocity of the ISS relative to the Earth's surface?

This was asked once before, but I believe there was no clear answer given and accepted. The ISS has an orbital period of 92.9 minutes, or 5574 seconds. If it were in a completely equatorial orbit, ...
1 vote
259 views

### What can possibly accelerate space elevator to these types of extreme velocities?

Is it possible for a space elevator not to just reach speeds of a few hundred km/h, but much faster. Since in the future, people might want to go up to GEO to maybe work there and come back home on ...
4k views

### Maximum velocity achieved by solar sail

What is the maximum (theoretical) velocity that can be achieved by solar-sail technology? Can we get close to the speed of light with that?
469 views

### Is the launch of a rocket slow because the change in velocity (delta_v) should be as small as possible because of energetic reasons?

Does it make sense to keep the launch of a rocket slow because the change in velocity (a.k.a. delta_v) should be as small as possible because of energetic reasons?
467 views

### Calculate velocity vector of elliptical orbit given the position vector at that point, the instantaneous speed, the true anomaly, and the inclination?

Sorry if this is obvious, but I am an amateur at orbital mechanics and trigonometry was never my strong suit. I would like to calculate the velocity vector at a point in an orbit given: position ...
1k views

### What's the motion of two connected satellites orbiting the Earth after their separation?

Let's consider the following problem (it's a job interview question): two satellites are orbiting the Earth in a circular orbit; they are rigidly linked by a tether which is always pointing in the ...
9k views

### If we can make an Alcubierre drive, how fast can it move a ship?

Assuming we ever manage to solve the energy generation problem (and whatever other problems may face it) and build a functioning Alcubierre drive, how "fast" would we be able to travel? That is, from ...
76 views

### Higher nozzle exit velocity generally means higher thrust right?

Higher nozzle exit velocity generally means higher thrust right? If that is the case, then a higher heat capacity could potentially lead to a higher exit velocity, thus higher thrust?
667 views

### orbital speed to maintain relative position to the Earth

I note that the orbital speeds of the planets slow down with increasing distance from the Sun. Say we have a space station orbiting the Sun at a distance of about 400 million kilometres (within the ...
533 views

### How fast could we go back to Uranus and Neptune?

Since SpaceX is making everything so much cheaper to launch into space. If we launch a pair of orbiters to Uranus and Neptune, how fast could they get there? They could be really light and small, so ...
111 views

### Will the initial velocity of an object in space get multiplied if a constant acceleration is applied? [closed]

Imagine an object travelling in space in the speed of 60 Kmph which took acceleration x if accelerated with the same x, will the object travel faster than 60 Kmph or travel in the same speed cuz of ...
145 views

### Could time illusion be used to send a spacecraft faster than the speed of light?

In this article (https://www.nasa.gov/feature/goddard/2022/hubble-spots-ultra-speedy-jet-blasting-from-star-crash) it says: The Hubble measurement showed the jet was moving at an apparent velocity ...
362 views

### At what point of travelling progressively faster around the Earth you are not going to fall back again?

My dad and I thought about a problem we had when discussing Earth's gravitational field. This wasn't the original question but I still would like to know the answer. So essentially my question is: Is ...
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### Minimum velocity needed to cross Karman line

When we travel in a car upwards on a slope (against gravity), we can keep driving the car at a constant speed without accelerating (without changing its speed). Theoretically, the only thing we need ...
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### Point Ahead Angle and Doppler Shift Frequency Changes Calculation with the tangential/radial velocity component for Inter-Satellite Link

While calculating the Point Ahead Angle we work with Tangential Velocity vector component and to calculate the Doppler shift i.e changes in frequencies, we work with Radial Velocity Vector component. ...
266 views

### Exact speed/distance of JWST (& others in L1/L2 halo) from Earth; is it measured any differently than for more distant deep-space missions?

How is the exact speed and distance from Earth of the JWST or any spacecraft in a Sun-Earth L1/L2 halo orbit determined? While deep space missions require ranging at hundreds of millions of kilometers ...
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### What is the fastest we could travel in space, or have ever traveled in space?

What is the fastest vehicle currently in space? With our current technology, at what point does physics start to restrict our speed in space?
536 views