Answer:
Facilitated diffusion and active transport both utilize proteins to transport substances across membranes. Differences between active transport and facilitated diffusion 1. Active transport requires an input of energy, usually ATP, while facilitated transport does not.
Answer: The result of "the upper bound of the density" does not go on the denominator.
So simplified, no. The answer is no.
A protostar reaches equilibrium when gravity is balanced by the outward force of nuclear fusion.
Momentum is conserved if and only if sum of all forces which are exserted on system equals zero. In our situation there are only internal forces, so by Newton's third law their vector sum is 0.
So 
.
Kinetic energy of system at first: 
. After: 
. The secret is that other energy is in work of deformation forces (they in turn heat a bullet and a block).
Answer is A)
