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3 years ago

Piaget used a pendulum apparatus to assess whether children had reached the _____ stage of cognitive development.

Physics

1 answer:

Savatey [412]3 years ago

6 0

Answer:

formal operational

Explanation:

The Formal operational thinking has tested experiments using the pendulum. The method involved three factors (variables) the length of the string, the weight of the object and the force or impulse that is printed on it. The task was to find out which factor is most important to determine the swing speed of the pendulum. Children who have already reached the formal operational stage solve the task systematically, testing one variable at a time.

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Which characteristic is common to all permanent magnets?

yanalaym [24]

I can't eliminate answers. Some of them are just wrong. A is incorrect. There is no such thing as a 1 pole magnet.

I wouldn't use B. If it is just a bar it is not a magnet.

C is the traditional answer

D is a space filler. It is just there to occupy a letter.

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3 years ago

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Granite is mostly used in building work places whereas Gneiss is used for making tombstones, flooring, etc. Why do you think so?

lozanna [386]

Answer:

Granite is durable, as it is hard and tough.

Gneiss has resistance to pressure and mechanical impacts

Explanation:

Granite is an igneous rock. It is mostly used in building works and construction because they are very durable. They are hard and tough and they have no internal structures.

Gneiss is used for flooring, ornamental stone, tombstones because of the fact that it shows resistances to pressure and also mechanical impacts.

<u>how they are formed in nature:</u>

In nature, granite is formed from the cooling down of hot molten magma and it's solidification before it reaches the surface of the earth.

In nature, gneiss is as a result of igneous rock or sedimentary rocks metamorphosing. Gneiss and granite are kind of similar. When subjected to great heat, granite becomes gneiss

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3 years ago

Can someone help me on question 1?

grigory [225]

In question 1, both of your answers are correct, but I don't understand the process you went through in the 'a' part.

R = v/I . That's a correct formula.
But it doesn't help you in this form, because you need to find I
So turn it into a helpful form ... Solve it for I, so it says I=something.

R= v/I

Multiply each side by I : R I = V.

Now divide each side by R: I= V/R .
THERE'S the equation you want.

I = V / R

I = 1.5 / 10 = 0.15 Amp.

That's slightly cleaner, although I don't really understand what you were actually thinking in that part.

But again ... You answered both parts correctly, and your process in b is fine.

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3 years ago

A practical rule is that a radioactive nuclide is essentially gone after 10 half-lives. What percentage of the original radioact

ArbitrLikvidat [17]

Answer:

0.09 % of the original radioactive nucllde its left after 10 half-lives
It will take 241,100 years for 10 half-lives of plutonium-239 to pass.

Explanation:

The equation for radioactive decay its:

$N ( t) \ = \ N_0 \ e^{ \ - \frac{t}{\tau}}$ ,

where N(t) its quantity of material at time t, $N_0$ its the initial quantity of material and $\tau$ its the mean lifetime of the radioactive element.

The half-life $t_{\frac{1}{2}}$ its the time at which the quantity of material its the half of the initial value, so, we can find:

$N (t_{\frac{1}{2} }) \ = \ N_0 \ e^{ \ - \frac{t_{\frac{1}{2}}}{\tau}} \ = \frac{N_0}{2}$

so:

$\ N_0 \ e^{ \ - \frac{t_{\frac{1}{2}}}{\tau}} \ = \frac{N_0}{2}$

$e^{ \ - \frac{t_{\frac{1}{2}}}{\tau}} \ = \frac{1}{2}$

$- \frac{t_{\frac{1}{2}}}{\tau}} \ = - \ ln( 2 )$

$t_{\frac{1}{2}}\ = \tau ln( 2 )$

So, after 10 half-lives, we got:

$N ( 10 \ t_{\frac{1}{2}}) \ = \ N_0 \ e^{ \ - \frac{10 \ t_{\frac{1}{2}}}{\tau}}$

$N ( 10 \ t_{\frac{1}{2}}) \ = \ N_0 \ e^{ \ - \frac{10 \ \tau \ ln( 2 ) }{\tau}}$

$N ( 10 \ t_{\frac{1}{2}}) \ = \ N_0 \ e^{ \ - 10 \ \ ln( 2 ) }$

$N ( 10 \ t_{\frac{1}{2}}) \ = \ N_0 \ * \ 9.76 * 10^{-4}$

So, we got that a 0.09 % of the original radioactive nucllde its left.

Putonioum-239 has a half-life of 24,110 years. So, 10 half-life will take to pass

$10 \ * \ 24,110 \ years \ = \ 241,100 \ years$

It will take 241,100 years for 10 half-lives of plutonium-239 to pass.

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A description of both speed and direction

julia-pushkina [17]

Speed most often describes acceleration or a high rate of motion. ... As a verb, it means to “move along quickly,” like how you speed around on your bike. Direction is defined as the path that something takes, the path that must be taken to reach a specific place, the way in which something is starting to develop or the way you are facing

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