Answer:
The depth of focus achievable with those lenses is small.
Explanation:
A larger aperture makes it much harder to focus on more than one object. When using a telephoto lens (the ones the question is referring to), the depth of focus is very small. For example, using a telephoto lens to take a photo of a runner might get the runner in focus, but certainly not the track, or the audience behind them. If you look at photos, especially older photos, of Olympians in almost any sport you can see this.
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Answer:

Explanation:
Hello.
In this case, since the velocity is computed via the division of the distance traveled by the elapsed time:

The distance is clearly 1743 km and the time is:

Thus, the velocity turns out:

Which is a typical velocity for a plane to allow it be stable when flying.
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Refer to the diagram shown below.
Still-water speed = 9.5 m/s
River speed = 3.75 m/s down stream.
The velocity of the swimmer relative to the bank is the vector sum of his still-water speed and the speed of the river.
The velocity relative to the bank is
V = √(9.5² + 3.75²) = 10.21 m/s
The downstream angle is
θ = tan⁻¹ 3.75/9.5 = 21.5°
Answer: 10.2 m/s at 21.5° downstream.
O2 refers to two oxygen atoms bonded together, while 2 O refers to two oxygen atoms that are not bonded to each other. They both have two oxygen atoms, but in O2, the oxygen atoms are bonded, while in 2O, the atoms are not.
Answer:
59.51 mph.
Explanation:
The following data were obtained from the question:
Distance (d) = 147 miles
Time (t) = 2.47 hours.
Speed (S) =?
Speed is defined as the distance travelled per unit time. Mathematically, it is expressed as:
Speed (S) = Distance (d) / time (t)
S = d/t
With the above formula, we can obtain the speed of the girl as illustrated below:
Distance (d) = 147 miles
Time (t) = 2.47 hours.
Speed (S) =?
S = d/t
S = 147 miles / 2.47 hours.
S = 59.51 miles per hour (mph)
Thus, the speed of the girl is 59.51 mph.