Answer:
1. 1, 2, 4 all show some form of refraction as the bending of a light ray when passing from one media to another.
Explanation:
Number 4 is the most accurate as it also shows some light being reflected and the bending of the refracted light ray in the correct direction for going from a medium of low refractive index (air) into a higher refractive index material (crown glass)
v = x/t
v = average velocity, x = displacement, t = elapsed time
Given values:
x = 6km south, t = 60min
Plug in and solve for v:
v = 6/60
v = 0.1km/min south
Answer:
the magnitude of the work done by the two blocks is the same.
Explanation:
The work done by block a on block b is given by:

where Fa is the force exerted by block a on block b, and d is the distance they cover.
The work done by block b on block a is given by:

where Fb is the force exerted by block b on block a, and d is still the distance they cover.
For Newton's third law, the force exerted by block a on block b is equal to the force exerted by block b on block a, therefore

and so

Time period = time/no. of waves = 6/3 = 2s
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