In: Physics
A circular rock 5 km in radius hits the earth head-on, at speed 36 km/s. The rock's density is 3 g/cm3. The earth's mass is 6*1024 kg. Treating the earth as initially stationary, calculate its final in speed due to the impact.
Because of the system's trouble with small numbers, calculate the speed in μm/s -- the distance unit is the micron or micrometer, 10-6 meter.
I am so confused on where to start, like is the rocks density m2 and earths mass m1? please help