<p>If the comet is on a parabolic trajectory, then its total energy (kinetic plus gravitational potential) is zero. This enables you to solve for the perihelion distance if you know the perihelion velocity (or vice-versa). The comet always travels at the escape speed appropriate for its distance from the Sun.</p>

<p>This and other useful properties of parabolic trajectories are discussed on the appropriate <a href="http://en.wikipedia.org/wiki/Parabolic_trajectory" rel="nofollow">wikipedia page</a>.</p>

CC BY-SA 3.0
2015-05-27T10:54:28.947Z
2015-05-27T10:54:28.947Z
ProfRob
<p>Comet on the parabola orbit flies by Sun.</p>

<p>I would like to know what is comet's full energy? What is its distance from Sun at perihelion?</p>

CC BY-SA 3.0
2015-05-27T09:11:33.060Z
This question is too vague? Which comet? The title is not explained in the post.
ProfRob
CC BY-SA 3.0
2015-05-27T09:13:26.343Z
any of. Its perihelion speed is 94 km/s.
EFmiza
CC BY-SA 3.0
2015-05-27T09:59:12.223Z
thts all I ve got
EFmiza
CC BY-SA 3.0
2015-05-27T23:28:20.967Z
Are these homework problems? If so, you should disclose that. It seems that such a question would be accompanied by a diagram.
andy256
<orbit><earth><comets>
How much time comet is within the Earth's orbit?
EFmiza
# How much time comet is within the Earth's orbit?

(Asked by: username_0 on 2015-05-27)

Comet on the parabola orbit flies by Sun.

I would like to know what is comet's full energy? What is its distance from Sun at perihelion?

**Tags:** orbit, earth, comets
> **Comments:**
> **username_1**: This question is too vague? Which comet? The title is not explained in the post.  
> **username_0**: any of. Its perihelion speed is 94 km/s.  
> **username_0**: thts all I ve got  
> **username_2**: Are these homework problems? If so, you should disclose that. It seems that such a question would be accompanied by a diagram.  

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## 1 answers

### Answer by username_1 on 2015-05-27. Score: 3 | Accepted answer

If the comet is on a parabolic trajectory, then its total energy (kinetic plus gravitational potential) is zero. This enables you to solve for the perihelion distance if you know the perihelion velocity (or vice-versa). The comet always travels at the escape speed appropriate for its distance from the Sun.

This and other useful properties of parabolic trajectories are discussed on the appropriate [wikipedia page](http://en.wikipedia.org/wiki/Parabolic_trajectory).


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