They are: n? m2/kg2； n？ m2？ Carbon-2 compound
(2) Let the acceleration of gravity on the planet surface be g, which can be obtained from the planation motion.
tanθ=yx=gt2v0①
So g=2v0tanθt
For celestial bodies on the surface of the planet, gmmr 2 = mg 2.
So R=GMt2v0tanθ.
For a "near-Earth satellite" that makes uniform circular motion around the planet, it should be mg=mv2R③.
By who? ① ② ③ Type? v=gR=42GMv0tanθt④
(3) The stress situation is shown in the figure. The magnitude and direction of the force exerted by QA and QB on QC do not change because of the existence of other charges, and still obey Coulomb's law.
The force of QA on QC: FA=KQAQCL2, like charges repel each other.
QB acts on QC: FB=KQBQCL2, and opposite charges attract each other.
∵QA=QB=Q∴FA=FB
According to the parallelogram rule, the force F 1 on QC is the resultant force of FA and FB. According to geometry knowledge, the force on QC is F 1=FA=FB=KQQCL2=KQqL2.
The direction is parallel to the AB line to the right.
Answer: (1) The units of constants G and K in the law of universal gravitation and Coulomb's law are: n? m2/kg2； n？ m2？ c-2；
(2) In order to prevent the object from falling back to the planet surface, the object should be thrown at a speed of at least 42GMv0tanθt;
(3) The electrostatic force on the charge QC=+q at the vertex C is KQqL2, and the direction is parallel to the AB line to the right.