# Tag Info

## New answers tagged space-travel

2

I suspect that you may be under the mistaken impression that there is no gravity in space. This is a common belief since we all can see the astronauts floating in "zero g" when on the ISS are some other spacecraft. However, we can easily dispense with this misconception by asking "what keeps the ISS in orbit around the Earth if there is no gravity?". Of ...

0

The escape velocity from earth (the speed required for an object to leave earth completely, i.e. travel infinitely far away) is 11.2 km/s. If the object has a smaller velocity it will return eventually. Unless an object is launched straight up, it also has a sideways velocity. This means that it will not fall back directly on top of the launcher. If it ...

4

That's exactly the case. If you look at the trajectory of any given spacecraft, you will see that it has a few burns of the rocket engines punctuating very long periods just coasting along in orbit around some other body. For example, the flight path of Apollo 8 has something like eight different rocket burns: launch, translunar and transearth injection (to ...

0

Usually you should denote miles by "mi" and meters by "m" to avoid confusion. 600,000 Mi/h translates into 268km/s (kilometers per second) so I'll use that figure, and assume that it is the speed of rotation of the sun around the center of the milky way. You would have just as much "motion" as if you were in outer space, due to the principle of relativity. ...

1

Hints: $30 \,km \, s^{-1}$ is about $\dfrac{1}{10000}$ times the speed of light and more precisely $\dfrac{30000}{299792458}$ times Distance of $4.2$ light years Number of years neded is ...

1

1 year is approximately $y = 3.15 \times 10^7 s$, and light travels at $c = 3.00\times 10^5 km/s$, so convert the speed of the space probe in km/s into ly/s and then into ly/y. Note that \$\frac{km}{s} = \frac{km}{s} \left(\frac{3.15 \times 10^7s}{1 y}\right) \times \left(\frac{ly}{3.00\times 10^5 km/s \times 3.15 \times 10^7s}\right) = \frac{1}{30.0\times ...

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