(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Evil Alien has put an Asteroid with

mass of 1,000,000kg to destroy mankind.

Distance from center of the Earth to Asteroid

(assume negligible center) is

10^8m and lets the gravitational force do the work.

Earth radius is 6.4 x 10^6m

and its mass is 5.98 x 10^24kg.

If the atmosphere extends out to 500km beyond

the surface and exrts an average friction force of 10^8N,

calculate the speed of the asteroid just before it hits the ground.

(Assume the asteroid rtains all of its mass as it travels through the atmosphere)

2. Relevant equation

Fgrav = Gm1m2/r^2

3. The attempt at a solution

I tried to use F=ma first

by doing it so I get

F=Gm1m2/r^2=m1a

a=Gm2/r^2

However, could not do anything more since there is no dt.

So, I tried taking an integral of it,

finding the work and set it equal to kinetic energy

(not sure whether indefinite/definite integral matters)

integral of Gm1m2/r^2 = -Gm1m2/r

-Gm2/r^2=v^2

but got this and it cannot happen

because v^2 cannot be - number...

v=i(imginary)

I am stuck at this point have no

further suggestion on what I should do.

I've been working on it for about an hour

and would appreciate any help.

Thanks in advance

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# Using Gravitational constant to get the final velocity

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