# friction problem

Discussion in 'MCAT Study Question Q&A' started by FRANK1985, 11.17.10.

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1. ### FRANK1985

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Hey guys, help needed, here goes

A meteor with a mass = 1Kg moving at 20km/s collides with jupiter's atmosphere. the meteor penetrates 100 km into the atmosphere and dsintegrates. What is the average force on the meteor once it enters Jupiter's atmosphere (ignore gravity)?

a) 2*10^3 N
b) 4*10^3 N
c) 8*10^3 N
d) 2*10^5 N

thank you

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A?

4. ### FRANK1985

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that's correct, But i don't get it

1/2mv^2= F*d
1/2 * 1 * (20)^2 = F * 100km

200 = F* 100km
F= 200/100
F= 2N

what am I doing wrong????

5. ### ModernAlchemistTransform and Transcend 7+ Year Member

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Convert Km to m in both the velocity and the displacement.

6. ### FRANK1985

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DUH!!!! I AM SO RETARDED! thank u so much

7. ### ModernAlchemistTransform and Transcend 7+ Year Member

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Don't worry about it haha. That has happened to me about 1 million times.

8. ### panda2queen

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hey I know this was posted a while back, but I am hoping someone can clarify this problem a little for me. I thought that you would use the equation Fdcos(theta) and cos of 0 is just one so then I thought this was set to equal the change in kinetic energy plus the change in potential energy so it would be F*d = delta K + delta U....how come above you just did F*d = delta K...where did the change of potential energy go?

thanks!

9. ### TcDroid4med 2+ Year Member

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the question says to ignore gravitational force