Answer:
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Answer:Principle of rectilinear propagation of light
Explanation:Principle of rectilinear propagation of light
Rectilinear propagation of light refers to the propensity of light to travel along a straight line without any interference in its trajectory. ... It is because light travels along a straight line and leaves only the areas where the object interferes.
Answer:
B. 17.15 watts
Explanation:
Given that
Time = 10 seconds
height = distance = 0.7 meters
weight of sack = mg = F = 245 newtons
Power = work done/ time taken
Where work done = force × distance
Substituting the given parameters into the formula
Work done = 245 newton × 0.7 meters
Work done = 171.5 J
Recall,
Power = work done/time
Power = 171.5 J ÷ 10
Power = 17.15 watts
Hence the power expended is B. 17.15 watts
This question involves the concepts of average speed, distance, and time.
The average speed of the family is "2.5 mi/hr".
<h3>AVERAGE SPEED</h3>
The average speed is defined as the ratio of the total distance covered with the total time taken to cover it.
![v=\frac{s}{t}](https://tex.z-dn.net/?f=v%3D%5Cfrac%7Bs%7D%7Bt%7D)
where,
- s = distance covered = 2.5 miles
- t = total time taken = 1 hour
- v = average speed = ?
Therefore,
![v=\frac{2.5\ mi}{1\ hr}](https://tex.z-dn.net/?f=v%3D%5Cfrac%7B2.5%5C%20mi%7D%7B1%5C%20hr%7D)
v = 2.5 mi/hr
Learn more about average speed here:
brainly.com/question/12322912