Pls help :( this is really hard and I need to pass this grade lol

Answer:

Rubidium or Rb

Explanation:

Use the periodic table, the period numbers are number of shells while the group numbers are numbers of valence electrons

Answer:

B. raising the temperature of the air

Answer:

vector quantity............

Explanation:

Mark me braimlist

Answer:

scalar

Explanation:

Answer:

your answer will be the letter B

Answer:  The primary function of the thalamus is to relay motor and sensory signals to cerebral cortex It also regulates sleep, alertness, and wakefulness.

Explanation:

The primary function of the thalamus is to relay motor and sensory signals to cerebral cortex It also regulates sleep, alertness, and wakefulness.

Answer:

A. electrical to light

Explanation:

A jumbo-tron video is a very large television that is most times fitted into walls and displayed along the main roads. It has a light-emitting display(LED) property. Energy transformation is the conversion of energy from one form to another.

The video screen just as a regular television in the house emits light, sound and heat energies. Electrical energy which flows from one end to another powers the jumbo-tron video screen and is thus converted into light, heat and sound energies.

The energy transformation that takes place when a jumbo-tron video screen shows an instant replay is electrical to light energy.

Energy transformation is the conversion of energy from one form to another.

Hence the energy transformation that takes place when a jumbo-tron video screen shows an instant replay is electrical to light energy.

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Answer:

14,653 J.

Explanation:

We know that,

Total mechanical energy is equal to the sum of all the potential and kinetic energies.

Given,

Kinetic energy when a car jumps off a ramp= 5000 J

Potential energy = 4685 J

Potential energy when the car lands= 4968 J

TME = 5000 + 4685 + 4968

        = 14,653 J

Hence, the car's total mechanical engery is equal to 14,653 J.

Answer: Wrong

Explanation:

The statement that accurately describes  the relationship between bond strength and the melting and boiling points of a substance is; "substances held together by ionic bonding have higher melting  and boiling points than those held together by hydrogen bonding."

Intermolecular forces refers to forces of attraction that holds molecules together in a particular state of matter. The nature and magnitude of intermolecular forces impacts on the magnitude of the melting and boiling points of substances.

Substances held together by ionic bonding have higher melting  and boiling points than those held together by hydrogen bonding. The bonds between ionic substances can only be broken at very high temperature.

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Answer:B

Explanation:

A P E X

The diagram in which there is no current in the electric wire is B, the reason behind that it is not connected with the battery.

When put in an electromagnetic field, charged matter experiences a force due to the fundamental property of electric charge. Positive or negative electrical ions are possible.

When two charge are in opposition to one another, they repel one another. The term "neutral" refers to an object has no net charge. The early understanding of the way charged particles interact is now referred to as classical electrodynamics, and it is still true for issues that do not demand for taking into account quant phenomena.

Electrical charge is a preserved attribute, meaning that the net charged of an isolated system—that is, the sum of the positive and negative charges—cannot change. Particles at the subatomic level carry an electric charge.

The second diagram from the option will have no current in it because the wires are not connected with the battery, so the flow of current will not take place.

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Answer:

c

Explanation:

Answer:

20.4 [tex]m/s^{2}[/tex]

Explanation:

To start doing this problem, first draw a free body diagram of the table. My teacher always tells us to do this, and I find that it is very helpful. I have attached a free body diagram to this answer- take a look at it.

First, let us see if Net force = MA. To do that, we need to determine whether the object is at equilibrium horizontally. For an object to be at equilibrium, it either needs to be moving at a constant velocity or not moving at all. Also, if an object is at equilibrium, there will not be any acceleration. But we know that there IS acceleration horizontally, so it cannot be in equilibrium. If it is not in equilibrium, we can use the formula ∑F= ma.

Let us determine the net force. Since the object is moving horizontally, we can ignore the weight and normal force, because they are vertical forces. The only horizontal forces we need to worry about are the applied force and force of friction.

Applied force = 1055 N (490 + 565)

Friction force= Unknown

To find the friction force, use the kinetic friction formula, Friction = μkN

μk is the coefficient, which the problem includes- it is 0.613.

N is the normal force, which we have to find.

*To find the normal force, we have to determine if the object is at equilibrium VERTICALLY. Since it has no acceleration vertically (it's not moving up/down), it is at equilibrium. Now, when an object is at equilibrium in one direction, it means that all the forces in that direction are equal. What are our vertical forces? Weight (mg) and Normal force (N). So it means that the Normal force is equal to the Weight.

Weight = mg = (40)(9.8) = 392 N

Normal force = 392 N

Now, plug it back into the formula (μkN): (0.613)(392) = 240.296 N

Friction = 240.296 N

Now that we know the friction, we can find the horizontal net force. Just subtract the friction force, 240.296 from the applied force, 1055 N

Horizontal Net Force: 814.704 N

Now that we know the net force, plug in the numbers for the formula

∑F= ma.

814.704 = (40.0)(a)

*Divide on both sides)

a = 20.3676 m/s^2

Round it to 3 significant figures, to get:

20.4 [tex]m/s^{2}[/tex]

Answer:

A black hole is a region of spacetime where gravity is so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it.[1] The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.[2][3]

The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, according to general relativity it has no locally detectable features.[4] In many ways, a black hole acts like an ideal black body, as it reflects no light.[5][6] Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe directly.

Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace.[7] The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Black holes were long considered a mathematical curiosity; it was not until the 1960s that theoretical work showed they were a generic prediction of general relativity. The discovery of neutron stars by Jocelyn Bell Burnell in 1967 sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.

Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses (M☉) may form. There is consensus that supermassive black holes exist in the centers of most galaxies.

The presence of a black hole can be inferred through its interaction with other matter and with electromagnetic radiation such as visible light. Matter that falls onto a black hole can form an external accretion disk heated by friction, forming quasars, some of the brightest objects in the universe. Stars passing too close to a supermassive black hole can be shred into streamers that shine very brightly before being "swallowed."[8] If there are other stars orbiting a black hole, their orbits can be used to determine the black hole's mass and location. Such observations can be used to exclude possible alternatives such as neutron stars. In this way, astronomers have identified numerous stellar black hole candidates in binary systems, and established that the radio source known as Sagittarius A*, at the core of the Milky Way galaxy, contains a supermassive black hole of about 4.3 million solar masses.

On 11 February 2016, the LIGO Scientific Collaboration and the Virgo collaboration announced the first direct detection of gravitational waves, which also represented the first observation of a black hole merger.[9] As of December 2018, eleven gravitational wave events have been observed that originated from ten merging black holes (along with one binary neutron star merger).[10][11] On 10 April 2019, the first direct image of a black hole and its vicinity was published, following observations made by the Event Horizon Telescope in 2017 of the supermassive black hole in Messier 87's galactic centre.[12][13][14]

Blackness of space with black marked as center of donut of orange and red gases

The supermassive black hole at the core of supergiant elliptical galaxy Messier 87, with a mass about 7 billion times that of the Sun,[15] as depicted in the first false-colour image in radio waves released by the Event Horizon Telescope (10 April 2019).[16][12][17][18] Visible are the crescent-shaped emission ring and central shadow,[19] which are gravitationally magnified views of the black hole's photon ring and the photon capture zone of its event horizon. The crescent shape arises from the black hole's rotation and relativistic beaming; the shadow is about 2.6 times the diameter of the event horizon.[12]

Schwarzschild black hole

Simulation of gravitational lensing by a black hole, which distorts the image of a galaxy in the background

Gas cloud being ripped apart by black hole at the centre of the Milky Way (observations from 2006, 2010 and 2013 are shown in blue, green and red, respectively).[20]

Answer:

Sam is providing the biggest power i.e. 50 W

Explanation:

Sam is moving house and is carrying a 300N box of books up a flight of steps 5m high, it takes her 30 seconds.

Sam's power :

[tex]P_1=\dfrac{W_1}{t_1}\\\\P_1=\dfrac{F_1d}{t_1}\\\\P_1=\dfrac{300\times 5}{30}\\\\P_1=50\ W[/tex]

Gary follows her carrying a bag of clothes doing 1000 J of work; it only takes him 25 seconds.

Gary's power :

[tex]P_2=\dfrac{W_2}{t_2}\\\\P_2=\dfrac{1000}{25}\\\\P_2=40\ W[/tex]

So, it is clear that Sam is providing the biggest power.

The earth receives energy from the sun in one day than all the energy consumed by humans in one year.

The sun provides around 174 petawatts of energy to Earth, of which 89 petawatts is absorbed by the planet.

The Global energy consumption is roughly 15 terawatts annually.

Thus, we can conclude that, the earth receives energy from the sun in one day than all the energy consumed by humans in one year.

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Answer:

Thomson's model showed an atom that had a positively charged medium, or space, with negatively charged electrons inside the medium. After its proposal, the model was called a "plum pudding" model because the positive medium was like a pudding, with electrons, or plums, inside.

Answer:

21s

Explanation:

Given parameters;

Radius  = 10m

Speed or velocity  = 3m/s

Unknown:

Period  = ?

Solution:

To solve this problem, use the expression:

      v  = [tex]\frac{2\pi r}{T}[/tex]  

r is the radius

T is the unknown

           Input the parameters and solve for T;

    3  = [tex]\frac{2 x \pi x 10}{T}[/tex]  

    62.84 = 3T

         T  = 21s

Explanation:

Opposite side from the 41° angle = 15.24m

We wish to find the adjacent side (horizontal length)

Therefore 15.24m / tan41° = 17.53m.

Answer:

there are not all safe for humans

Answer:

   v = 0.6 v₁

Explanation:

This is an exercise in collisions, let's start by defining a system formed by the two bodies, so that the forces during the collisions have been internal and the momentum is preserved.

Instant starts. Before the crash

       p₀ = M v₁ + m 0

Final moment. After the crash

       [tex]p_{f}[/tex] = (M + m) v

how momentum is conserved

       p₀ = p_{f}

       M v₁ = (M + m) v

       v = [tex]\frac{M}{M+m} v_{1}[/tex]

let's calculate

       v = [tex]\frac{15}{15+10} v_{1}[/tex]

        v = 0.6 v₁

Explanation:

The unit of volume derived from SI units(1) is the cubic meter, m3.

Chemists in a laboratory usually deal with much smaller volumes than cubic meters and the metric but non-SI units of liter or litre (L) and milliliter or millilitre (mL or ml) are in common use.

In 1964 the litre was redefined as being equal to exactly 1 cubic decimetre:

1 L = 1 dm3

So 1 milliltre = 1 cubic centimetre

1 mL = 1 cm3 (= 1cc)

Other metric units of measuring volume are given in the table below:

large volume → → → → → → → → → → small volume

name teralitre gigalitre megalitre kilolitre hectolitre decalitre decilitre centilitre millilitre microlitre nanolitre picolitre femtolitre attolitre

symbol TL GL ML kL hL daL dL cL mL µL nL pL fL aL

volume (L) 1012 L 109 L 106 L 103 L 102 L 101 L 10-1 L 10-2 L 10-3 L 10-6 L 10-9 L 10-12 L

Answer:

p=w/t

160/8=20

80/4=20

180/9=20

...so..all these uses equal power

Answer:

[tex]\leq 40[/tex]

Explanation:

So if you’re going 40mph, your speedometer may read up to 50.25mph - but it can never read less than 40mph. In order to stay within the law, carmakers calibrate their speedometers to slightly overreport their vehicles' speeds.

Answer:

professional communication style is expected to be formal while the casual is informal.

Explanation:

Answer:

365

Explanation:

A calendar is equal to a year and it is 365 days in a year.

Answer:

a basis or standard for evaluation, assessment, or comparison; a criterion.

Explanation:

Definition of reference point. : something that is used to judge or understand something else The professor used the study as a reference point for evaluating and discussing other theories.

Answer:

something that is used to judge or understand something else

Explanation:

The professor used the study as a reference point for evaluating and discussing other theories.