5. Mrs. Purel 's 5" grade class wanted to know how the Egyptians moved the huge stones to make the pyramids.
The class watched a video on how the pyramids were
made. The students saw the stones of different sizes sitting
on large tree trunks being moved down a path. What forces
would be present when the stones are being moved?
A. The forces applied to the stone objects of different masses
are gravity, pushes and friction.
B. The forces applied to the stone objects of different masses
are gravity, pushes or pulls and friction.
C. The forces applied to the stone objects of different masses
are friction and gravity.
D. The forces applied to the stone objects of different masses
are pulls and pushes, friction and gravity.

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

i dont have a visual in front of me, but i can you reason to try to get the right one. the graph should look like this, 0 to 6 there is a spike, 12 to 14 there should be a very low point. slight increase in the graph at 12 to 14, and flat 14 to 18

explanation: