more physic problem!!!!!!!!!?

Question

You throw a rock of weight 21.0 vertically into the air from ground level. You observe that when it is a height 14.9 above the ground, it is traveling at a speed of 25.6 upward.
Part A
Use the work-energy theorem to find its speed just as it left the ground;
Take the free fall acceleration to be = 9.80 .
m/s





Part B
Use the work-energy theorem to find its maximum height.
Take the free fall acceleration to be = 9.80 .

Answer 1

The change in potential energy due to elevation is m*g*∆h. The kinetic energy is .5*m*v^2. The total energy at height h is then m*g*h+.5*m*v^2. The total energy when it was at ground level is .5*m*v0^2; these must be equal so .5*m*v0^2 = m*g*h+.5*m*v^2. Solve for v0 to get v0 = 2√(m*g*h+.5*m*v^2)/m

Its maximum height occurs when all of the kinetic energy is converted to potential energy. From the above you got v0; the initial energy was then .5*v0*2 and this must = m*g*hmax; so hmax = (.5*v0^2)/(m*g)

Answer 2

the galaxies rotate at speeds inconsistent with their glaring mass is because we do see all of it. i'm touching on it as being the theoretical darkish count number. There are very solid proofs that exhibits that darkish count number exist. One the is the inconsistent speed of and glaring mass. darkish count number makes up about seventy 5% to 80% of the count number in the Universe...