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# The Earth takes one year to orbit the Sun at a distance of 1.5 x 10^11 m. Calculate i watch

1. The Earth takes one year to orbit the Sun at a distance of 1.5 x 10^11 m. Calculate its speed.

Speed = distance/time

(1.5 x 10^8)/ (365*24*60*60) = 4.75646... kms-1

Why is the answer in the book 29.9 kms-1?
2. Because your title has to the power 11 and your working has to the power 8, maybe?

Either work in metres or km.
3. distance is wrong. you've used the radius not circumference.

basically you've calculated what the average speed of the earth would be if it took a year to crash directley into the sun
4. Like, really really fast.
5. (Original post by DumpOrStay?)
Because your title has to the power 11 and your working has to the power 8, maybe?

Either work in metres or km.
I changed the distance to km because the answer in the book is given in km. If I do the same sum with x10^11 it's just 1000 x bigger
6. i =
7. (Original post by didgeridoo12uk)
distance is wrong. you've used the radius not circumference.

basically you've calculated what the average speed of the earth would be if it took a year to crash directley into the sun
Ah ok.

So the distance given is the radius? So the correct sum would be

(2 x pi x 1.5x10^8) / (365*24*60*60)

= 29.8857...

Yay

Thanks
8. The motion is circular, so you must find the circumference of the orbit first.

Pi x diamter = 3.14 x (2x1.5x10^8)=9.24x10^8.

Then use speed = distance/time

Speed = 9.24x10^8) / (365x24x60x60)=29.885 kms^-1

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