How was the rotation rate of mercury determined?

The rotation rate of the mercury are determined by the radar used by the scientists. The reflected beam of the radar are showed by the doppler broadening. The rotational period of the mercury on its axis are rotates slow as compared to orbital period.

Basically, the rotational period of the mercury takes 59 earth days to rotate about its axis.  

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

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