Which of the following methods of improving air quality does not require advanced technology?

zhannawk [14.2K]

The six commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium....

7 0

4 years ago

When a board with a box on it is slowly tilted to larger and larger angle, common experience shows that the box will at some poi

eimsori [14]

Answer: The force of kinetic friction is smaller than that of static friction, but F_g remains the same.

Explanation:

The situation is same as when a book is pushed with an increasing force on a table; When the force is low, book doesn't move, until that under a given force starts moving, and then it goes on movement even if the force decreases a bit.

The physical explanation for this, that friction force adopts any value needed to avoid to move the object, till a limit value is achieved, called static friction force, equal to the normal force times the static friction coefficient.

Once in movement, the kinetic friction coefficient replaces the static one , and in general is lower than the static one, so the force diminishes.

In the case of the box sliding down the board, the force that tries to move the object down the board, is the component of the weight parallel to the board, that can be showed that being equal to the weight times the sinus of the angle of the board with the horizontal, as follows:

F_g = m g sin θ

When θ increases, F_g does the same, so friction force always has the same magnitude than F_g (but opposite direction) so the box doesn't move, till that θ takes a value that produces a F_g equal to static friction force.

Beyond this limit angle, F_g (remaining the same for a given angle) is greater than the kinetic friction force, and the box slides.

In the limit, when θ=90º, sin θ =1⇒ F_g = mg, so the object is in free fall.

6 0

4 years ago

1. An astronaut in a spacesuit has a mass of 80 kilograms. What is the weight of this astronaut on the surface of the Moon where

Andrews [41]

Weight = 80 x (9.8/6) = .... N

8 0

3 years ago

What might happen if water molecules did not have a slight negative charge on one end and a slight positive charge on the other?

Katena32 [7]

Answer:

It would not be possible the cohesion among water molecules by the polar covalent bonding.

Well, to understand this in a better way, let's begin by explaining that water is special due to its properties, which makes this fluid useful for many purposes and for the existence of life.

In this sense, one of the main properties of water is cohesion (molecular cohesion), which is the attraction of molecules to others of the same type. So, water molecule ( $H_{2}O$ ) has 2 hydrogen atoms attached to 1 oxygen atom and can stick to itself through hydrogen bonds.

How is this possible?

By the polar covalent bonding, a process in which electrons are shared unequally between atoms, due to the unequal distribution of electrons between atoms of different elements. In other words: slightly positive and slightly negative charges appear in different parts of the molecule.

Now, it can be said that a water molecule has a negative side (oxygen) and a positive side (hydrogen). This is how the oxygen atom tends to monopolize more electrons and keeps them away from hydrogen. Thanks to this polarity, water molecules can stick together.

5 0

4 years ago

Doug is doing work. Without knowing exactly what he is doing, which can be said about the work he is doing?

WARRIOR [948]

<h3>Answer;</h3>

<em>Energy is transferred.</em>

<h3>Explanation;</h3>

Work is the force applied over a given distance, in other words work is the product of force and distance. That is; Work = force × distance.
Work is measured in Joules.

Energy on the other hand, is the ability to do work.

According to the principle of work-energy a change in the kinetic energy is equivalent to the net work don e by the object. Therefore, when work is being done energy is being transferred from one point to another.

8 0

4 years ago

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