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3 years ago

1. Who first published the classification of the elements that is the basis of our periodic table today?

1 answer:

4 0

That particular group of elements is reffered to as the "Noble Gasses"--a title that comes from the fact that these gases are very "secure" and don't mix well with other elements.

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Kilogram is a unit of volume.<br> a. True<br> b. False

Helga [31]

B. False

because kilogram is the unit of mass.

7 0

4 years ago

What is the efficiency of a 0.60 kg basketball that, one dropped from a 2.0 m height (from basket rim) , rebounds to 1.2 m in he

Zinaida [17]

<h2>Let us find the efficiency : Ans = 0.6</h2>

Explanation:

we know :

efficiency = output/input

We also know that :

output = m x g x h

where :

m = mass of body

g = acceleration due to gravity

h = height of body from floor

Thus, output = 0.6 x 10 x 1.2 = 7.2J

Similarly ,input = 0.6 x 10 x 2 = 12J

Thus efficiency = 7.2/12 = 0.6

4 0

3 years ago

An airplane is flying 340 km/hr at 12o east of north. the wind is blowing 40 km/hr at 34o south of east. what is the plane's act

jok3333 [9.3K]

Define an x-y coordinate system such that
The positive x-axis = the eastern direction, with unit vector $\hat{i}$ .
The positive y-axis = the northern direction, with unit vector $\hat{j}$ .

The airplane flies at 340 km/h at 12° east of north. Its velocity vector is
$\vec{v}_{1} = 340(sin(15^{o})\hat{i} + cos(15^{o})\hat{j} ) = 88\hat{i} + 328.4\hat{j}$

The wind blows at 40 km/h in the direction 34° south of east. Its velocity vector is
$\vec{v}_{2} =40(cos(34^{o})\hat{i} - sin(24^{o})]\hat{j}) = 33.1615\hat{i} -22.3677\hat{j})$

The plane's actual velocity is the vector sum of the two velocities. It is
$\vec{v}=\vec{v}_{1}+\vec{v}_{2} = 121.1615\hat{i}+306.0473\hat{j}$

The magnitude of the actual velocity is
v = √(121.1615² + 306.0473²) = 329.158 km/h

The angle that the velocity makes north of east is
tan⁻¹ (306.04733/121.1615) = 21.6°

Answer:
The actual velocity is 329.2 km/h at 21.6° north of east.

5 0

3 years ago

What does it mean for their to be a net force on an object vs no net force? Which one is described as balanced forces and which

STatiana [176]

It’s like the force put against something or someone✨

3 0

3 years ago

What is direct current? In which direction does current go according to the electron flow convention?

KatRina [158]

Answer:

Answer to the question is:

Explanation:

Direct Current:

It is that current where electrons circulate in the same amount and sense in time, that is, flowing in the same direction. Its polarity is invariable and causes a current of relatively constant amplitude to flow through a load. This type of current is known as direct current (DC), and is generated by a battery.

the current of electrons will leave the negative terminal of the battery, (because they repel each other and also repel free electrons in the copper conductor), and go to the positive terminal where there is a lack of electrons, passing through the circuit to which it is connected. In this way the electric current is produced.

4 0

3 years ago