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

The gravitational pull of the earth on an object is inversely proportional to the square of the distance of the object from the center of the earth. At the earth's surface this force is equal to the object's normal weight mg, where g=9.8m/s^2, and at large distances, the force is zero.

a) If a 30000kg asteroid falls to earth from a very great distance away, how much kinetic energy will it impart to our planet? You can ignore the effects of the earth's atmosphere.

b) What will be its minimum speed as it strikes the earth's surface?

2. Relevant equations

F=Gm1m2/r

sqrt(2K/m)

3. The attempt at a solution

I've tried to put the variables in equation F=Gmm/r and I'm using the Earth's radius from Wikipedia = 6371km. Should I be using m1=m2=30000kg? Plus I don't know how to get kinetic energy out of the force equation.

For part b I need to know the kinetic energy.

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# Kinetic energy problem (masteringphysics)

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