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Which scientist most likely studied tadpole cells under a microscope? a.SchwannB.JanssenC.HookeD.Schleiden

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# Tag: scientist

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A scientist needs to know the temperature of the water every 5 m along 3 km of the river. What tool would the scientist use?

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Identify the scientist that discovered the theory of evolution

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During an experiment on frog embryos,a scientist removes a few cells from the neural tube. What effect would this have on the embryo

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**Answer:**

1) Water has very high specific heat.

2) It expands when it freezes

3) ability to dissolve in ionic substances

4) Water molecules at the surface experience fewer hydrogen bonds than water molecules within the liquid.

**Explanation:**

1) Water molecules due to their high specific heat , undergo relatively less increase in temperature after absorbing heat. So they prevent their adjoining area to experience sharp increase in temperature.

2) Water is an example which expands on freezing. In it , large spaces are left between molecules when it cools. It happens because hydrogen bonds prevent any two molecules to come very close thereby creating gaps. This gap is filled up when ice melts , which results in overall reduction in volume of water.

3) Uneven distribution of charge results in water molecules becoming polar in nature . A polar substance can be dissolved in polar solvents only.

4) It is due to property of surface tension. Property of surface tension results due to molecules of water near the surface experiencing a net downward force due to hydrogen bonds . It is due to fewer hydrogen bonds made by them.

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**Keywords:
**

*Polynomial, identify, ascending order*

For this case, we must identify the polynomial that is written in ascending order. If we want to order a polynomial of ascending form, we must organize the polynomial from least to greatest exponent. By definition, a polynomial is of the form:

Where:

a, b, c, d, e, f: They are the coefficients of the polynomial

n, n-1,3,2,1,0: They are the exponents. This polynomial is of degree “n”, because “n” is the largest exponent.

x: It is the variable

Then, we must see among the options given a polynomial written from least to greatest exponent, that is, from the form:

So, among the options we have:

written ascending

**Answer:
**

**Option C**

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The scientist is incorrect in his statement.

The new seafloor is formed at places where there’s divergent plate boundaries. Because the two or more plates are moving away from one another, the crust becomes thinner, so the high temperatures, pressures, and magma manage to penetrate from the mantle very easily. The magma that comes out on the surface is cooling off very quickly and is creating igneous rocks, thus new crust, or new seafloor if you will.

The trenches are appearing at places of convergent plate boundaries, and they are not places where new seafloor is formed, but rather places where one tectonic plate submerges under another tectonic plate.

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Fg=(G*m₁*m₂)/r₂, where G=6.67*10^-11 m³ kg⁻¹ s⁻² is the gravitational constant, m₁ and m₂ are the masses of the two bodies and r is the distance between those bodies.

Due to the gravitational attraction the pencil and the eraser will attract if we there is no friction on the surface.

m₁=10 g=0.01 kg is the mass of the pencil

m₂=20 g=0.02 kg is the mass of the eraser

r=2.5 cm = 0.025 m

First we calculate the Fg:

Fg={(6.67*10^-11)*0.01*0.02}/(0.025²)=2.1344*10^-11 N

To get the velocity v of the pencil:

v²=2as, where a is the acceleration of the pencil and s is the path. In our case s=r so we can write:

v²=2ar

a=Fg/m₁= 2.133*10^-9 m/s²

v²=2*(2.133*10^-9)*0.025=1.0665*10^-10

v=√(1.0665*10^-10)=1.0327*10^-5 m/s

We have the velocity and the acceleration, so we can calculate the time t with the equation:

t=v/a=(1.0327*10^-5)/(2.133*10^-9)=4841.6 s

1 hour has 3600 s so when we divide time t in seconds by 3600 we get time T in hours:

T=t/3600=4841.6/3600=1.3449 h.

So the time for the pencil and eraser to touch is T=1.3449 hours.

Also time T can be expressed like T= 1h and 20 mins and 41.64 s

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Fg=(G*m₁*m₂)/r₂, where G=6.67*10^-11 m³ kg⁻¹ s⁻² is the gravitational constant, m₁ and m₂ are the masses of the two bodies and r is the distance between those bodies.

Due to the gravitational attraction the pencil and the eraser will attract if we there is no friction on the surface.

m₁=10 g=0.01 kg is the mass of the pencil

m₂=20 g=0.02 kg is the mass of the eraser

r=2.5 cm = 0.025 m

First we calculate the Fg:

Fg={(6.67*10^-11)*0.01*0.02}/(0.025²)=2.1344*10^-11 N

To get the velocity v of the pencil:

v²=2as, where a is the acceleration of the pencil and s is the path. In our case s=r so we can write:

v²=2ar

a=Fg/m₁= 2.133*10^-9 m/s²

v²=2*(2.133*10^-9)*0.025=1.0665*10^-10

v=√(1.0665*10^-10)=1.0327*10^-5 m/s

We have the velocity and the acceleration, so we can calculate the time t with the equation:

t=v/a=(1.0327*10^-5)/(2.133*10^-9)=4841.6 s

1 hour has 3600 s so when we divide time t in seconds by 3600 we get time T in hours:

T=t/3600=4841.6/3600=1.3449 h.

So the time for the pencil and eraser to touch is T=1.3449 hours.

Also time T can be expressed like T= 1h and 20 mins and 41.64 s

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x(t) = 2.31 + 4.90t² – 0.10t⁶

If we are going to differentiate the equation in terms of x, we get the value for velocity.

dx/dt = 9.8t – 0.6t⁵

Calculate for the value of t when dx/dt = 0.

dx/dt = 0 = (9.8 – 0.6t⁴)(t)

The values of t from the equation is approximately equal to 0 and 2.

If we substitute these values to the equation for displacement,

(0) , x = 2.31 + 4.90(0²) – 0.1(0⁶) = 2.31

(2) , x = 2.31 + 4.90(2²) – 0.1(2⁶) = 15.51

Thus, the positions at the instants where velocity is zero are 2.31 and 15.51 meters.

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“Life as we know it is impossible without water.” Explain why a scientist might make this statement. Give two examples to support your answer.

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Adenine,guanine,cytosyne and thymine are the four nitrogenous bases present in the DNA of all organisms.Which scientist discored these bases?

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model, Rutherford’s model, Bohr’s model… and finally, Schrödinger’s theory.

Besides, keep

in mind that:

-When an atom

loses an electron, that electron has to end up in another atom, and then you

have cations and anions… and a cation always has to be near an anion… so they

are sort of keeping an eye on their missing electrons.

-The only situation

where we find isolated neutrons is during nuclear reactions… and remember those

are dangerous chain reactions! The atomic bomb is an example of that.

-We can have

isolated protons and we call them H+ – so it works as any other cation. You can

find H+ in water, where we also have OH-.

Let’s talk

about Thompson’s model: They call it the “plum pudding”. It consisted on a large positive charge (the pudding) filled

with little negative charges (the plums).

And this is Rutherford’s

model: He found out negative charges (electrons) were actually spinning around

the positive nucleus. But he didn’t say anything about the shapes or sizes of

their orbits.

Then you have

the Bohr’s model, also known as the planetary model. Bohr said that there are

smaller orbits, closer to the nucleus, and larger orbits, in the outer part of

the atom, and did propose a lot of detail about the orbits. But it still wasn’t

enough accurate.

Schrödinger’s

focused on finding more details about where in the atom you can find each

electron, its velocity, its momentum, etc.

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Answer:

A change in which chemical composition of the substance changes is known as a chemical change and said to have undergone a chemical reaction and a change in which only the physical properties of a substance change is known as a physical change.

Processes like cutting, grinding, phase change (melting, freezing, boiling) are all physical changes.

Processes like corrosion, burning are chemical changes.

__Physical change:__

A seed into seedling

wax melting from applied heat

grinding wheat to make flour

adding copper with gold to make jewelry

In all of the above examples, only the physical properties such as size, shape and phase has changed. hence, these are physical changes.

__Chemical reaction occurs in:__

making caramel by burning sugar

tarnishing of silver

A chemically different new product is being formed when substance undergoes a chemical reaction like in the above examples.

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A scientist counts 25 bacteria present in a culture and finds that the number of bacteria triples each hour. The function y = 25 ∙ 3x models the number of bacteria after x hours. Estimate when there will be about 1170 bacteria in the culture

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While looking at a cell under a microscope, a scientist is able to see a biological molecule. This molecule is a nucleic acid with double strands and contains the nitrogenous bases adenine, thymine, cytosine, and guanine. Based on this information, what conclusion can the scientist draw regarding this nucleic acid

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4,000 kg/m³ = (mass) / (0.09 m³)

Multiply each side

by 0.09 m³ : (4,000 kg/m³) x (0.09 m³) = mass

mass = 360 kg .

Force of gravity = (mass) x (acceleration of gravity)

= (360 kg) x (9.8 m/s²)

= (360 x 9.8) kg-m/s²

= 3,528 newtons .

That’s the force of gravity on this block, and it doesn’t matter

what else is around it. It could be in a box on the shelf or at

the bottom of a swimming pool . . . it’s weight is 3,528 newtons

(about 793.7 pounds).

Now, it won’t seem that heavy when it’s in the water, because

there’s another force acting on it in the upward direction, against

gravity. That’s the buoyant force due to the displaced water.

The block is displacing 0.09 m³ of water. Water has 1,000 kg of

mass in a m³, so the block displaces 90 kg of water. The weight

of that water is (90) x (9.8) = 882 newtons (about 198.4 pounds),

and that force tries to hold the block up, against gravity.

So while it’s in the water, the block seems to weigh

(3,528 – 882) = 2,646 newtons (about 595.2 pounds) .

But again … it’s not correct to call that the “force of gravity acting

on the block in water”. The force of gravity doesn’t change, but

there’s another force, working against gravity, in the water.

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**Explanation :**

The forces that govern all matter in the universe are :

(1) Gravitational force

(2) Electromagnetic force

(3) Strong nuclear force

(4) Weak nuclear force

The characteristics of the weak nuclear force are:

(1) These forces are stronger than gravity.

(2) These forces are effective only for short distances i.e. has a very small range.

(3) These forces are weaker than the electromagnetic force because electromagnetic force is about times that of weak nuclear force.

(4) These forces are responsible for radioactive decays. So, these forces are repulsive.

**So, final answer is :**

**is repulsive, has a very small range, is stronger than the gravitational force
**

**and is weaker than the electromagnetic force.**

**Hence, this is the required solution.**

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**a. (+4, -2)**

We can use the following conventions:

– x-axis: east-west direction, with east being positive x and west being negative x

– y-axis: north-south direction, with north being positive y and south being negative y

With this coordinates, the movie theater is:

– 4 km east –> this means x = +4

– 2 km south –> this means y = -2

So, the coordinates of the theater are (+4,-2)

**b. (-1,+1)**

We drive 5 km west (which means ) and 3 km north (which means ). We have to add these displacements to each coordinate. we find:

So, the coordinates of the restaurant are (-1, +1)

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**Answer: **Hello there!

we have the equation y = 1.09x, that describes the number of yards y in x meters.

a) Yes, if you have negative numbers of x (this means negative meters, this is used usually to denothe something that is behind the observer) then the equation transform them into negative yards.

b) in this case you want to know how many meters are in 40yd, then we replace y by 40yd in the equation:

40 = 1.09x

x = 40/1.09 = 36.7 meters

so in a 40yd race, there are 36.7 meters.

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