# Unknown Speed

Unknown Speed!!

Hi all, I've got this problem in my physics class I can't figure it out. Iv'e changed the values because I only wan't to know How we can solve this..

Here it goes:

I have a 400 g (3,29 N) Meteor that crashed in the earth surface and reach a depth of 1.7 m . The scientist say that the ground had a resistance force of 1,0 x 10^6 N.

(We ignore the air's friction.)

What was the meteor's speed?

It's all I've got.

Iv'e done a graphic on paper whit vectors But I don't quite get the methos of doing it.

Else.. I tried Caluculating the potiential energy (Ep = mgh) but I don't have the height.. Neither de speed for the Kinetic energy (Ek = 1/2 m v^2)

Bah.. Help me out! :P:P

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#### chroot

Staff Emeritus
Gold Member
Do you understand the relationship between force, distance, and work?

W = F*d

- Warren

OHHH !! nevermind.. I get it!I will start working on it.

Here is what I have done:

W= Fr * Delta Sr
W= 1000000 N * 1,7 m
W= 1700000 J

Ek = 1/2 * m * v^2
1700000 j = 0.5 * 3,29 N * v^2
1033434,65 j = v^2
1016,58 m/s = V

Meteor's speed is 1016,58 m/s

#### chroot

Staff Emeritus
Gold Member
Be careful with your units. Mass should be in kilograms, not in newtons. Otherwise, yes, you have the right idea.

- Warren

"Unknown Speed"

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