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- Homework Statement
- A small asteroid of mass m = 1.50 × 10^13 kg collides with the planet Mars. The speed of the asteroid when it was very far from the planet was 3.60 × 10^3 m/s. Given that Mars has a mass M = 6.42 × 10^23 kg and a radius R = 3.39 × 10^6 m, and that the gravitational constant G = 6.67 × 10^−11 Nm^2/kg^2 the speed at which the asteroid impacts the Martian surface is:

A) 8.63 × 103 m/s.

B) 4.29 × 103 m/s.

C) 6.18 × 103 m/s.

D) 7.15 × 103 m/s.

- Relevant Equations
- u=-GMm/r

k = mv^2/2

Since the radius is "very far", I cannot find the total mechanical energy by using the gravitational potential energy formula and find the kinetic energy at impact. I can't think of any other way to find final velocity without knowing the radius.