Stuck with physics

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Stuck with physics

Postby Andy » Mon Mar 05, 2007 7:46 pm

Does anyone know How far the sun is from the earth is it.
1light second
1light minute
9light minutes
9light days
1light year

Also how do you calculate how far a light year is in meteres.
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Postby Kentigern » Mon Mar 05, 2007 8:48 pm


Second question first!

Have you come across the equation d = vt (distance = velocity multiplied by time)?

If you have it is fairly straightforward to work out how far a light year is in metres.

One light year is the distance light travels in one year. I would imagine that you have been given the speed of light, which is 3*10^8m/s.

This means that you have a speed (the speed of light) and a time (one year, you need to convert this into seconds though as the speed of light is given n meters per second). Given this information, and the equation d = vt, you should be easily able to work out the distance in metres. Does that make sense?

As for the first question. you are given a variety of options in light-units.

1 light second means that it takes 1 second for light from the sun to reach the earth; 1 light minute means that it takes light 1 minute to reach the earth; and so on.

What you need to work out is how long light reaches to get from the sun to the earth.

You need the speed of light again (given above) and the distance between the sun and the earth in metres (which an internet search suggests is 1.49476*10^11m). You therefore have a distance and a speed, so you can workout the time by rearranging v=dt and substituting in the numbers.

Does all this make sense? Feel free to ask any questions if it doesn't!

Gordon :)
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Postby Andy » Tue Mar 06, 2007 8:25 pm

Thanks Kentigern It does make sense and I probably should have known it my physics is not so good I have a hopeless teacher and quite a disruptive class mind you I could study more instead of making excuses.
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Postby Katielauren2001 » Tue Mar 13, 2007 10:59 am

I don't understand Physics lol.
Dyspraxia is me I would never change that :)
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