Answer:
Planet, in which he concluded that Planet X had a mass roughly seven times that of Earth—about half that of Neptune—and a mean distance from the Sun of 43 AU. He assumed Planet X would be a large, low-density object with a high albedo, like the giant planets
Explanation:
Answer is B, it can be positive or negative, as long as it has a charge.
The independant variable is whats being changed. The dependant variable responds to that change, and the control variable stays the same.
Hope that helps!!!
Use conservation of momentum ;
m1u1 + m2u2 = m1v1 + m2v2
1200×15.6 + 0 = 2700v
v = 18720/2700
v = 6.933 or ~ 7 m/s