A 200. kg box is pulled at constant speed by the little engine pictured below.  The box moves a distance of 2.5 m across a horizontal surface.          

a)    Draw a force diagram of all relevant forces acting on the box.   
   
b)    Construct a qualitative energy bar graph/flow diagram for this situation.  Be sure to specify your system.

c)    How much energy is transferred by the engine?

d)    What type of motion would occur if the engine pulled with a force of 500 N?
    Modify your force diagram and apply Newton's 2nd Law.

answer: the correct answer is   air pressure at the top of mount everest is higher than at the bottom of the grand canyon.

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explanation:

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.