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1 year ago

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About three billion years ago, single-celled organisms called cyanobacteria lived in Earth’s oceans. They thrived on the ocean’s

abundance of ___ , which they used during the process of photosynthesis. Much later, this process allowed organisms, such as fish, to survive by extracting dissolved ___ from ocean waters.
a. oxygen
b.carbon dioxide
c. nitrogen

2 answers:

quester [9]1 year ago

6 0

The first blank is carbon dioxide, second one is oxygen

pickupchik [31]1 year ago

3 0

I think its Oxygen.
ancient cyanobacteria produced Earth's first oxygen-rich atmosphere, which allowed the eventual rise of eukaryotes. T<span>he chloroplasts of eukaryotic algae and plants are derived from cyanobacteria</span>

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A barbellbell is loaded with two 20 kg plates on its right side and two 20kg plates on its left side. The barbell is 2.2m long,

Aleks [24]

Answer:

<h2>Center of gravity of the system of all masses is 105 cm from the left end of the rod</h2>

Explanation:

Let the position of Left end of the rod is our reference

So here we will have

$m_1 = 20 kg$

$x_1 = 20 cm$

$m_2 = 20 kg$

$x_2 = 30 cm$

$m_3 = 20 kg$

$x_3 = 110 cm$

$m_4 = 20 kg$

$x_4 = (220 - 40) = 180 cm$

$m_5 = 20 kg$

$x_5 = (220 - 35) = 185 cm$

so we will have

$x_{cm} = \frac{m_1x_1 + m_2x_2 + m_3x_3 + m_4x_4 + m_5x_5}{m_1 + m_2 + m_3 + m_4 + m_5}$

$x_{cm} = \frac{20(20 + 30 + 110 + 180 + 185)}{20 + 20 + 20 + 20 + 20}$

$x_{cm} = 105 cm$

7 0

2 years ago

At what angle should the roadway on a curve with a 50m radius be banked to allow cars to negotiate the curve at 12 m/s even if t

just olya [345]

Answer:

The banking angle of the road is 16.38 degrees.

Explanation:

Given:

Radius of the roadway on curve, R = 50 m

velocity of the moving car, V = 12 m/s

The banking angle can be calculated by using the formula below:

If there's no frictional force, then net force is equal to centripetal force.

MgTanΦ = (MV^2)/ R

TanΦ = V^2 / gR

Where;

Φ is the banking angle

g is acceleration due to gravity

TanΦ = (12 x 12) / (9.8 x 50)

TanΦ = 0.2939

Φ = arctan (0.2939)

Φ = 16.38 degrees

Therefore, the banking angle of the road is 16.38 degrees.

3 0

2 years ago

If points a and b are connected by a wire with negligible resistance, find the magnitude of the current in the 12.0 v battery.

Marizza181 [45]

V = I * R
Where V is the voltage, I is the current and R is the resistance. Using Ohm's law, you require resistance to find the current through the wire. Technically, if the wire has a resistance of 0, you will get infinite current. But this isn't possible. Maybe the negligible resistance refers to the battery's internal resistance - not the wire's resistance.

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1 year ago

On a snowy day, max (mass = 15 kg) pulls his little sister maya in a sled (combined mass = 20 kg) through the slippery snow. max

sesenic [268]

Work done by a given force is given by

$W = F.d$

here on sled two forces will do work

1. Applied force by Max

2. Frictional force due to ground

Now by force diagram of sled we can see the angle of force and displacement

work done by Max = $W_1 = Fdcos\theta$

$W_1 = 12*5cos15$

$W_1 = 57.96 J$

Now similarly work done by frictional force

$W_2 = Fdcos\theta$

$W_2 = 4*5cos180$

$W_2= -20 J$

Now total work done on sled

$W_{net}= W_1 + W2$

$W_{net} = 57.96 - 20 = 37.96 J$

7 0

2 years ago

A quadraphonic car stereo operates on electric current provided by the car's 12V battery and is connected in series. Each channe

yKpoI14uk [10]

Answer:

2.93 A

Explanation:

From Ohm's law V = IR where V = voltage = 12 V, I = current = ? and R = resistance = 4.1 Ω.

So, the current in each quadraphonic stereo circuit is I = V/R = 12 V/4.1 Ω = 2.93 A

3 0

1 year ago