Which is the satellite terra able to do?
a) monitor the movement of comets and meteorites
b) monitor seismic activity on the moon
c) monitor the orbit of mars
d) monitor volcanic eruptions on earth

The Terra satellite was sent to space on December 18, 1999 and is still there in 2016. The satellite is able to monitor volcanic eruptions on Earth. The correct answer is D. 

Refer to the diagram shown below.

The given data is

mass, kg   Coordinates. m
-------------   -----------------
   2               (0, 0)
   2               (2, 0)
   4               (2, 1)

Total mass, M = 2+2+4 = 8kg
Let (x,y) be the coordinates of M.

Then, taking moments about the origin, we obtain
8x = 2*0 + 2*2 + 4*2 = 12
x = 1.5 m

8y = 2*0 + 2*0 + 4*1 = 4
y = 0.5 m

  (1.5, 0.5) m