Abundant energy: Fusing atoms together in a controlled way releases nearly four million times more energy than a chemical reaction such as the burning of coal, oil or gas and four times as much as nuclear fission reactions (at equal mass)
Wildlife researcher starts from a and then reaches b, he turns towards north 40 degree to move towards c.
Total displacement is ac
Total horizontal displacement = 4+4 cos40 =7.06 km
Total vertical displacement = 4 sin40 =2.57 km
Total displacement 
= 7.51 km
If the distance to a point source of sound is doubled, by a multiplicative factor of 4, the intensity changes.
Intensity of sound is the sound which is perpendicular to sound wave propogation per unit area. It is dependent on the Surface of source sound.
Intensity is the Power per unit area. Its SI unit is Watt/m².
As we move away from a source of sound, the sound starts to diminish. This is due to the decreasing sound intensity with distance.
It can also be understood by the fact that on increasing distance, the Power radiated by the source spreads over a larger area. Hence, the Intensity decreases gradually.
Since, Intensity is proportional to the square of the distance.
Hence, on doubling the distance, Intensity reduces to one fourth of the initial intensity or reduces by a multiplicative factor of 4.
Learn more about Intensity here, brainly.com/question/17583145
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Radio waves, Middle-C, and halitosis are not forms of light.
