All categories

2 years ago

Why is acceleration negative in a free fall?

2 answers:

6 0

Technically speaking altitude is measured from the ground up.
Therefore, say you're falling from 1000 metres, that number decreases till it reaches 0. Therefore, you're accelerating but towards the ground i.e. towards 0.

Therefore acceleration is negative because you're travelling at -x metres per second and accelerating at -x metres per second^2

murzikaleks [220]2 years ago

5 0

Only because when most people work with vertical motion, they call the upward direction positive. So falling objects have negative velocity and acceleration. But if you prefer to call the downward direction positive, you have every right to do that. Then the force of gravity on a falling object, as well as its velocity and acceleration, are all positive, and its negative altitude steadily grows until it hits the ground.

You might be interested in

Explain how polarization of a cell increases the cell's internal resistance.<br>(2<br>2.

Mandarinka [93]

Answer:

Explanation: The chemical action that occurs in the cell while the current is flowing causes hydrogen bubbles to form on the surface of the anode. This action is called POLARIZATION. Some hydrogen bubbles rise to the surface of the electrolyte and escape into the air, some remain on the surface of the anode. If enough bubbles remain around the anode, the bubbles form a barrier that increases internal resistance. When the internal resistance of the cell increases, the output current is decreased and the voltage of the cell also decreases.

A cell that is heavily polarized has no useful output. There are several methods to prevent polarization or to depolarize the cell.

One method uses a vent on the cell to permit the hydrogen to escape into the air. A disadvantage of this method is that hydrogen is not available to reform into the electrolyte during recharging. This problem is solved by adding water to the electrolyte, such as in an automobile battery. A second method is to use material that is rich in oxygen, such as manganese dioxide, which supplies free oxygen to combine with the hydrogen and form water.

A third method is to use a material that will absorb the hydrogen, such as calcium. The calcium releases hydrogen during the charging process. All three methods remove enough hydrogen so that the cell is practically free from polarization.

LOCAL ACTION

When the external circuit is removed, the current ceases to flow, and, theoretically, all chemical action within the cell stops. However, commercial zinc contains many impurities, such as iron, carbon, lead, and arsenic. These impurities form many small electrical cells within the zinc electrode in which current flows between the zinc and its impurities. Thus, the chemical action continues even though the cell itself is not connected to a load.

Local action may be prevented by using pure zinc (which is not practical), by coating the zinc with mercury, or by adding a small percentage of mercury to the zinc during the manufacturing process. The treatment of the zinc with mercury is called amalgamating (mixing) the zinc. Since mercury is many times heavier than an equal volume of water, small particles of impurities weighing less than mercury will float to the surface of the mercury. The removal of these impurities from the zinc prevents local action. The mercury is not readily acted upon by the acid. When the cell is delivering current to a load, the mercury continues to act on the impurities in the zinc. This causes the impurities to leave the surface of the zinc electrode and float to the surface of the mercury. This process greatly increases the storage life of the cell.

6 0

3 years ago

wildlife biologists are working to save some unique birds in the forest of north georgia.which of these questions must be answer

Maru [420]

Extinct<span> might be a word you associate with animals that lived long ago, like the dinosaurs, but did you know that over 18,000 species are classified as "threatened" (susceptible to extinction) today? Scientists involved in wildlife conservation have a tough job; they are in charge of determining what needs to be done to prevent a species from becoming extinct. Habitat, food supply, and impacts of local human populations are just a few of the factors these scientists take into account. It is a lot to keep track of for a single location, but the job becomes even harder when it is a migratory animal. In this science project, you will get a firsthand look at their job. You will access </span>real<span> data about migratory birds and use satellite images to analyze their habitats, then come up with a conservation plan to protect the species from extinction.</span>

7 0

3 years ago

Find the angle for the third-order maximum for 591 nm wavelength light falling on a diffraction grating having 1460 lines per ce

Marat540 [252]

Answer:

15.32°

Explanation:

We have given the wavelength $\lambda =591nm=591\times 10^{-9}m$

Diffraction grating is 1460 lines per cm

So $d=\frac{10^{-2}}{1460}=6.71\times 10^{-6}m$ (as 1 m=100 cm )

For maximum diffraction

$dsin\Theta =m\lambda$ here m is order of diffraction

So $6.71\times 10^{-6}sin\Theta =3\times 591\times 10^{-9}$

$sin\Theta =0.264$

$\Theta =15.32^{\circ}$

6 0

2 years ago

Compare the inner core and the outer core?

vfiekz [6]

To compare the inner core and the outer core, we need to outline the parameters based on

Temperature - the outer core has 2000-5000 C, while inner reach 6000 C
Structure and consistency - The outer core consist of iron and nickel, mix with low amount of gold, platinum, and uranium, while inner is the melting pot of all dense material and lot of uranium.
Depth - The outer core has depth to 2900 km, while inner core has 1300 - 1400 km radius.

<h3>Further explanation</h3><h3>Consistency / materials</h3>

Both the outer core and the inner core are made generally of iron and nickel.

<h3 /><h3>Temperature</h3>

The outer core achieves a temperature of 2000°c. The inward center has a temperature as high as 5000°c.
The inner core achieves a temperature of 6000 °c.
Within this temperature, both nickel and iron are dissolved and converted into a fluid.

<h3>Structure</h3>

In contrast to the outer core, the internal base is reduced in spite of the boiling temperature achieved the radioactive rot of uranium due to the incredible weight that keeps this layer in a stable stage.
The layer that partitions the external center and internal center is known as Bullen brokenness. Bullen brokenness is likewise the most sizzling locale of wherein the temperature reaches up to 6000°c its as hot as the outside of the sun.

<h3>Depth </h3>

Outside the outer and inner core, there is mantle that has the depth to around 2,900 kilometers from the Earth's surface.
The outer has depth more than 2900 kilometers from Earth surface.
The iner core is the deepest among all of them and has radius for 1300 kilometers.
Check the structure of earth here brainly.com/question/2162876

<h3>Structure of Earth</h3>

The Earth is separated into four layers. The external layer is the hull, beneath the covering is the mantle, and pursued by the external center, at that point, the most profound and the most smoking layer is known as the internal center.

<h3>Learn more</h3>

Here are the four layers of the Earth

Hull
Mantle
External center
Internal center

<h3>1. Hull or crust </h3>

The hull is the peripheral and the thinnest layer which goes about as the skin of the Earth that stretches out from the surface to around 32 kilometers beneath. This is the layer where we live, and volcanoes, quake, and mountain reaches are framed.

The marine shell is denser and more slender contrasted with mainland hull.
Mainland hull is thicker and is less thick contrasted with the maritime shell.

<h3>2. Mantle </h3>

Underneath the outside is the layer known as the mantle, which stretches out to around 2,900 kilometers from the Earth's surface. The coat is the thickest layer of the Earth and is progressively thick contrasted with the outside. It is the path more sizzling than the covering and equipped for liquefying it. The upper mantle is plastic, its made up of magma that as a result of an excessive amount of warmth it streams which causes changes on the outside of the Earth.

<h3>3. Outer Core </h3>

The external center is 2900 kilometers underneath the outside of the Earth. It is for the most part comprised of iron and nickel; however, in the fluid stage and its temperature ranges to about 2000°C. Regardless of whether the external center has a high weight, yet because of its a lot higher temperature, nickel and iron are liquefied. The external center is streaming outside the internal center, which produces an attractive field that shields the Earth from the hazardous, radioactive material originating from the warmth of the sun.

<h3>4. Internal Core </h3>

The internal center is the most profound layer comprised of heavy iron and nickel and has a sweep of around 1,300 kilometers. Its temperature scopes to about 5000°C. The internal has the most elevated thickness contrasted with the other. The warmth in the inside of the Earth is brought about by the radioactive rot of uranium in the internal center, which discharges considerable measure of heat.

Perhaps you are interested within the topic of

Seismic wave : brainly.com/question/2840246

Vulcanoes mountain : brainly.com/question/9164146

<h3>Core Curriculum category</h3>

Subject : Geography

Class : 8

Subchapter : Earth and its structure.

4 0

3 years ago

Read 2 more answers

Why are the temperatures on each of the other terrestrial planets more extreme than earth?

netineya [11]

Other terrestrial planets have more extreme temperatures mainly because of their atmospheres
Explanation:
for example the atmosphere of Venus is composed mainly of carbon dioxide, this carbon dioxide traps the heat or energy from the sun and makes the planet have higher temperatures. where on mars the atmosphere is very thin so it takes in lots of heat and doesn't keep it in very well so it gets very hot and very cold

7 0

3 years ago