Answer:
At an angle of 
Explanation:
Assume the river flows from East to West so for the swimmer to cross across it, assume he crosses it from West to East.
The resultant speed will be given by

Answer:
send the wagon down a higher hill
That's a weird graph, but judging from the units the acceleration is the slope of the graph.
a = (0.8 - 0.3)/(0.16 - 0.055) = 4.76 m/s²
If a star is moving towards Earth, shift towards the blue end of the spectrum, this is called blue shift. If the star is moving away from Earth the light from that star will be red and is called red shift .
The faster a star moves towards the earth, the more its light is shifted to higher frequencies. In contrast, if a star is moving away from the earth, its light is shifted to lower frequencies on the color spectrum
if a star is moving towards Earth, it appears to emit light that is shorter in wavelength compared to a source of light that isn't moving. Because shorter wavelengths correspond to a shift towards the blue end of the spectrum, this is called blue shift.
If the star is moving away from Earth, its light will lose energy to reach Earth, therefore the light from that star will be red and is called red shift
learn more about blue shift :
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