What is the primary reason fusion is not used in power plants? a. fussion causes too much air pollution 2. fission creates more energy than fussion c. the cost of using fussion in a practical way is too expensive d. currently technology is unable to control the reaction.

The correct answer is D, Current technology is unable to control the reaction.

Fusion is a process when two small elements fuse together to form a large element. It is a fundamental process that occur on the Sun, in this process tremendous amount of energy is released, however its very difficult to initiate this process, as it require a large amount of energy to propagate, also once the process is initiate it becomes extremely difficult to control the process, and currently we are not able use the fusion process in the power plant.

Therefore the correct answer is Currently technology is unable to control the reaction.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

total distance/total time

(85 + 82)/(5+3)

167/8

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