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Molodets [167]
3 years ago
6

Some life forms move so slowly that their movement cannot be detected by normal observation. The best way to determine any movem

ent is by placing a mark at some point, and observing any change in position from it. Why is this true?
Physics
2 answers:
romanna [79]3 years ago
5 0
Not sure the precise concept of "normal observation", but I assume that is observed by "eyes".

Eye observation is basically macroscopic, but when you use a mark, which can be regarded as a point of mass, then it goes to microscopic.

Mark is a reference point which you can compare the relative position change, but with your eyes, first you cannot notice microscopic changes, second the eyes cannot precisely set a stable reference point.
kirza4 [7]3 years ago
3 0

The mark is a reference point.

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The eiffel tower is a steel structure whose height increases by 19.5 cm when the temperature changes from −8 to +42 °c. what is
Readme [11.4K]
 The coefficient of expansion is 13 * 10^-6 m per meter length.per oK 
The temperature difference = 42 - - 8 = 50 oC 
delta T = (42 + 273) - (-8 + 273) = 50 oK 
delta L = L * 13* 10^6 m/oK 
oK = 50 oK delta L = 19.5 cm = 19.5 cm [1m / 100 cm] = 0.195m 
So we need to find the length and it is computed by:
0.195= L * 13 * 10^-6 * 50 L = 0.195 / (13*10^-6*50) L = 300 m 
6 0
3 years ago
Change the following data into scientific notation.<br><br> 5 000 000 km
RoseWind [281]
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3 years ago
You hold a bucket in one hand. In the bucket is a 500 g rock. You swing the bucket so the rock moves in a vertical circle 2.2 m
slavikrds [6]

Answer:v=3.28 m/s

Explanation:

Given

mass of rock m=500 gm

diameter of circle d=2.2 m

radius r=\frac{2.2}{2}=1.1 m

At highest Point

mg+N=\frac{mv^2}{r}

At highest Point N=0 because mass is just balanced by centripetal Force

thus mg=\frac{mv^2}{r}

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v=\sqrt{9.8\times 1.1}

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6 0
3 years ago
A truck covered 2/7 of a journey at an average speed of 40
sertanlavr [38]

Answer:

The amount of time for the whole journey is 8 hours.

Explanation:

A truck covered 2/7 of a journey at an average speed of 40  mph. Representing 1 the total of the trip traveled, then the rest of the distance traveled is calculated as: 1-\frac{2}{7} =\frac{5}{7}

So if the truck covered the remaining 200 miles at \frac{2}{7}, this means that \frac{5}{7} of the trip represents the 200 miles. So, to calculate the total distance traveled by the truck, you apply the following rule of three: if \frac{5}{7} of the route represents 200 miles, the integer 1 (which represents the total of the route), how many miles are they?

miles=\frac{1*200miles}{\frac{5}{7} } =\frac{7}{5} *200 miles

miles= 280

So the total distance traveled is 280 miles. Since speed is the relationship between the space traveled by an object and the time used for it (speed=\frac{distance}{time}), then if the average of the entire trip was 35 mph and the distance traveled 280 miles, the time is calculated as:

time=\frac{distance}{speed}=\frac{280 miles}{35 mph}

time= 8 h

<u><em> The amount of time for the whole journey is 8 hours.</em></u>

<u><em /></u>

6 0
3 years ago
tom does not reallt want to give away blue marbles and would like to change the probability that he chooses a blue marble to one
Llana [10]
We don't know how many of ANY color are in the bag right now, so there's no way to calculate an answer.

What Tom has to do is make sure that the number of marbles that are NOT blue is NINE TIMES the number of blue ones in the bag.
4 0
3 years ago
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