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2 years ago

How did photosynthesis start?

Physics

2 answers:

aleksklad [387]2 years ago

6 0

Answer:

Fossils of what are thought to be filamentous photosynthetic organisms have been dated at 3.4 billion years old. More recent studies, reported in March 2018, also suggest that photosynthesis may have begun about 3.4 billion years ago.

ycow [4]2 years ago

3 0

Answer:

Overwhelming evidence indicates that eukaryotic photosynthesis originated from endosymbiosis of cyanobacterial-like organisms, which ultimately became chloroplasts (Margulis, 1992). So the evolutionary origin of photosynthesis is to be found in the bacterial domain.

Explanation:

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Assume that the electric field E is equal to zero at a given point. Does it mean that the electric potential V must also be equa

lyudmila [28]

Answer:

No, this doesn't mean the electric potential equals zero.

Explanation:

In electrostatics, the electric field $\vec{E}$ is related to the gradient of the electric potential V with :

$\vec{E} (\vec{r}) = - \vec{\nabla} V (\vec{r})$

This means that for constant electric potential the electric field must be zero:

$V(\vec{r}) = k$

$\vec{E} (\vec{r}) = - \vec{\nabla} V (\vec{r}) = - \vec{\nabla} k$

$\vec{E} (\vec{r}) = - (\frac{\partial}{\partial x} , \frac{\partial}{\partial y } , \frac{\partial}{\partial z}) k$

$\vec{E} (\vec{r}) = - (\frac{\partial k}{\partial x} , \frac{\partial k}{\partial y } , \frac{\partial k}{\partial z})$

$\vec{E} (\vec{r}) = - (0,0,0)$

This is not the only case in which we would find an zero electric field, as, any scalar field with gradient zero will give an zero electric field. For example:

$V(\vec{r})= (x+2)^2 (y+4)^3 (z+5)^4$

give an electric field of zero at point (0,0,0)

8 0

3 years ago

The nucleus of a hydrogen atom is a single proton, which has a radius of about 1.2 × 10-15 m. The single electron in a hydrogen

Nutka1998 [239]

Answer: 0.86 × 10^14

Explanation:

Given the following :

Radius of proton = 1.2 × 10-15 m

Radius of hydrogen atom = 5.3 × 10-11 m

Density of proton could be calculated thus:

Mass of proton = 1.67 × 10^-27 kg

Using the formula :

(4/3) × pi × r^3

(4/3) × 3.142 × (1.2 × 10^-15)^3 = 7.24 × 10^-45

Density = mass / volume

Density = (1.67 × 10^-27) / ( 7.24 × 10^-45)

= 0.2306 × 10^18

Density of hydrogen atom:

Mass of hydrogen atom= 1.67 × 10^-27 kg

Using the formula :

(4/3) × pi × r^3

(4/3) × 3.142 × (5.3 × 10^-11)^3 = 6.24 × 10^-31

Density = mass / volume

Density = (1.67 × 10^-27) / ( 6.24 × 10^-31)

= 0.2676 × 10^4

Ratio is thus:

Density of proton / density of hydrogen atom

0.2306 × 10^18 / 0.2676 × 10^4 = 0.8617 × 10^14

6 0

3 years ago

Centripetal is a word used in science to mean

bogdanovich [222]

: the force that is necessary to keep an object moving in a curved path and that is directed inward toward the center of rotation a string on the end of which a stone is whirled about exerts centripetal<span> force on the stone — compare centrifugal force.</span>

7 0

3 years ago

Twin brothers, Andy and Brian, can mow their grandparents lawn together in 1212 minutes. Brian would mow the lawn by himself

Karo-lina-s [1.5K]

Answer:

It will take Andy 1.198minutes to mow the lawn and it will take Brian 1,209.98minutes to mow the same lawn.

Step-by-step explanation:

Using the simultaneous equation concept, let A denote Andy and B be Brian

Andy and Brian can mow the lawn for 1212minutes i.e A+B = 1212..eqn 1

If Brian would mow the lawn by himself in 1010 minutes more than it would take Andy, this means B=1010A...eqn 2.

Substituting eqn 2 into eqn 1

Equation 1 becomes

A+1010A=1212

1011A=1212

A=1212/1011

A=1.198

B = 1010×1.198

B=1,209.98

Therefore, It will take Andy 1.198minutes to mow the lawn and it will take Brian 1,209.98minutes to mow the same lawn.

6 0

3 years ago

If I toot 88 times what did that mean

Degger [83]

Answer:Nazi skinhead code for Heil Hitler. H being the 8th letter of the alphabet, therefore HH=88.

Explanation:

8 0

3 years ago