The value of a physical quantity is normally expressed as an implied product of a numeric value and a unit of measurement.
There are three categories to consider:
There is no explicit unit of measurement included. Examples of this would include index of refraction of a medium and the specific gravity of a substance (which is ratio of the density of the material divided by the density of some reference material, usually water at some specified temperature). In this category, there is an implied measurement unit of 1 . It is usually not written because 1 times any number is that same number, so it is pointless to write the “times 1”. The value of an index of refraction is simply a number, and that number is all you write for the quantity value. That number is the numerical value of the physical quantity. It is only slightly more complicated for specific gravity, because you are dividing one density by another, and both values should be expressed in the same units of measurement, and the division of one by the other cancels out those units, leaving you with 1 as the overall measurement unit.
For plane angles, there is a relationship between the length s of the arc of a circle, the radius r of that circle, and the angle a subtended by the arc at the circle center:
a = s/r
with the angle a being measured in the unit of radians. (To write the formula for some other angular unit requires incorporating a numeric factor, which is basically a conversion factor from radians to degrees,) Thus, if you have a circle of radius 3 m and an arc of 6 m on that circle, the the angle subtended or formed is:
(6 m)/(3 m) = 2, but we said this is the number of radians, so it is 2 rad.
Notice, we are dividing a length by a length (both the arc length and the radius being lengths), so if we use the same measurement unit for both lengths (regardless that unit being meters, feet, parsecs, or anything else), the two units cancel each other out upon division. This means that the unit we are calling radian is like with specific gravity in #1—it has the value 1. Indeed, we see the formula gives us 2 and we know that it is 2 rad, and the only way we can have them be the same, 2 rad = 2, is if the unit radian is actually just a funny, special name for the number 1. Why do we give the number 1 a special name here, unlike in category #1? That is because some inexperienced people find the concept of radian to be strange and inconvenient. They would rather use degrees, or arcminutes, or arcseconds, or semicircles, or some other such unit, and they all have different sizes. For example, a full circle is 2π rad and it is also 360°. Therefore, since both equal one circle of rotation, they must be equal to each other:
360° = 2π rad. Divide both sides by 360 to get:
1° = (2π/360) rad = (π/180) rad. Now, we saw above that rad = 1, so:
1° = (π/180) rad = (π/180) × 1 = π/180.
Thus, like the radian, the degree is also a number—not 1 though, but rather π/180, which cannot be “thrown away” because π/180 times a number does not yield back the original number.
Thus, 30° = 30 × π/180 = π/6 = π/6 × 1 = π/6 rad.
This is the explanation as to when we express an angle in degrees, we must write the ° symbol or spell out degrees, whereas when we express the angle in radians, we may either explicitly write rad or we may leave it off. Unfortunately secondary school geometry textbooks do not seem to understand this point and typically leave off the mandatory ° symbol. That usually gets straightened out when radians are presented—typically later in the second year of algebra or in trigonometry, but it becomes something necessary for students to unlearn the incorrect and learn the correct. Thus, if an angular unit is included, you can convert that angular unit into a real number and multiply by the numeric part of the physical quantity value to the the numeric value of the physical quantity. (And absence of angular unit implies radians, which have numeric value 1, so the numeric value of the quantity is just the numeric value that is present.
Solid angles work similarly, involving area divided by area. The steradian (sr) is the unit that has value 1.
How are the oscillating magnetic and electric fields of an electromagnetic wave positioned relative to each other?
Answer:
Electromagnetic waves consist of both electric and magnetic field waves. These waves oscillate in perpendicular planes with respect to each other, and are in phase. The creation of all electromagnetic waves begins with an oscillating charged particle, which creates oscillating electric and magnetic fields.
Explanation:
write si units of the following physical quantities volume , potential difference, temperature, electrical resistance
Answer:
cubic meter - Volume
Volt - potential difference
kelvin - temperature
ohm - electric resistance
Explanation:
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What is SI unit?give examples
Answer:
The system of units which is agreed by the International Conference of Scientists held in France in 1960 A.D is called SI unit.
What's Centripetal force................
Answer:
a force that acts on a body moving in a circular path and is directed towards the centre around which the body is moving.
Answer:
A centripetal force is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path.
I need chapter one section three
Two representative elements are in the same period of the periodic table. Which statement correctly describes the atoms of the two elements?(1 point)
They have the same number of valence electrons.
They have the same number of valence electrons.
They have valence electrons in different energy levels.
They have valence electrons in different energy levels.
They have valence electrons in the same energy level.
They have valence electrons in the same energy level.
They have the same number of electrons.Helium is in group 18 of the periodic table. How is helium different from the other elements in this group?(1 point)Helium atoms have valence electrons in the first energy level, while atoms of the other elements in the group have valence electrons in the second energy level.
Helium atoms have valence electrons in the first energy level, while atoms of the other elements in the group have valence electrons in the second energy level.
Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.
Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.
Helium atoms have a full outer energy level, while atoms of the other elements in the group do not have a full outer energy level.
Helium atoms have a full outer energy level, while atoms of the other elements in the group do not have a full outer energy level.
Helium atoms have 2 electrons, while atoms of the other elements in the group all have 18 electrons.
Use the periodic table to answer the question.
Which element has atoms with valence electrons in a higher energy level than those of calcium (Ca)?
lithium (Li)
lithium (Li)
cesium (Cs)
bromine (Br)
oxygen (O)
Use the periodic table to answer the question.
Which statement best describes the arrangement of electrons in an atom of fluorine (F)?
There are seven electrons in the first energy level and two electrons in the second energy level.
There are seven electrons in the first energy level and two electrons in the second energy level.
There are five electrons in the first energy level and two electrons in the second energy level.
There are five electrons in the first energy level and two electrons in the second energy level.
There are two electrons in the first energy level and seven electrons in the second energy level.
There are two electrons in the first energy level and seven electrons in the second energy level.
There are two electrons in the first energy level and five electrons in the second energy level.
Elements in the periodic table are arranged in the increasing order of their atomic number.
An atom will contain equal amount of protons and electrons. If two elements are in same period of periodic table then these elements will have same number of electrons.
Helium is one of the seven elements which are called as noble gases. This gas is odorless, tasteless and colorless which makes it unique from other elements.
It has two valence electrons while atoms of other elements in the group have 8 valence electrons.
Lithium has one valence electron, while calcium atom has 2 valence electrons.
The highest level of energy is due valence electrons of an atom. The correct answer is Lithium.
Fluorine element has 9 electrons. There are 2 electrons in the first energy level and seven electrons in the second energy level.
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what do you mean by acceleration of a body 10\s?
Answer:
it means that the body is moving with acceleration increased of 10m in every second.
If Bert the Bat travels eastward at 40 mph with a tailwind of 6 mph, what is his actual speed?
Answer:
36 mph.
Explanation:
Now Albert here is using the wind to his advantage but if say there was no wind then he would not have the 6 mph behind him so we subtract 6 from 40 to get 36. hope this helps :)
write down the symbols of nitrogen and neon?
Answer:
Nitrogen is N, neon is Ne
Answer:
Symbol of Nitrogen is N symbol of Neon Ne.
Write an ecosystem report on rain.
Answer:
Explanation:
kopkpo
2000 Pieces of paper are used everyday at a local school. Each piece of paper is 600cm^2. Convert the area of all the paper used in one day to m^2. The answer is 120 m^2 someone please help me understand this with dimensional analysis?
Which option is a negatively charged ion?
chlorite
chloride
chlorate
chlorine
We have that Chloride is is a negatively charged ion
Giving the the correct option as
Option B
From the Question we are Given
Chlorite
This is a form sheet silicate minerals that grown in nature
Chloride
This is is a negatively charged ion
Chlorate
This is a positively charge ion
Chlorine
This is an element that has an atomic number of 17
Therefore
Chloride is is a negatively charged ion
Giving the the correct option as
Option B
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how many seconds are there in 1 day . solve along with steps
One minute has 60 seconds, One hour has 60 minutes and one day has 24 hours. Thus, 80 x 60 x 24 = 86,400 sec
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Answer:
[tex]thank \: you[/tex]
a) A car accelerates uniformly at 3.7 m s⁻² as it passes a stationary road train. The initial speed of the car is 30 m s⁻¹, and it reaches the speed limit of 130 km h⁻¹ as it passes the front of the cab. Calculate the length of the road train. Give your answer to 3 significant figures. include units in your answer.
b) The braking distance of a road train travelling at 15 m s⁻¹ is 70 m. Assuming that the same deceleration is applied at all speeds, calculate the braking distance of a road train travelling at 25 m s⁻¹
(a) The length of the train is 54.6 m
(b) The braking distance of the road train is 194.44 m
The given parameters:
acceleration of the car, a = 3.7 m/s²
initial velocity of the car, u = 30 m/s
final velocity of the car, v = 130 km/h = 36.11 m/s
To find:
the length of the trainThe length of the train is the distance travelled by the car
The distance traveled by the car is calculated as:
[tex]v^2 = u^2 + 2as\\\\2as = v^2 - u^2\\\\s = \frac{ v^2 - u^2}{2a} \\\\where;\\\\s \ is \ the \ distance \ travelled \ by \ the \ car\\\\s = \frac{(36.11)^2 - (30)^2}{2\times 3.7} \\\\s = 54.585 \ m\\\\s \approx 54.6 \ m[/tex]
Thus, the length of the train is 54.6 m
(b) The braking distance of a road train travelling at 25 m s⁻¹
[tex]a = \frac{v_1^2}{2s_1} = \frac{v_2^2}{2s_2} \\\\Given;\\\\s_1 = 70 \ m\\\\v_1 = 15 \ m/s\\\\v_2 = 25 \ m/s\\\\s_2 = ?\\\\2s_2v_1^2 = 2s_1v_2^2\\\\s_2 = \frac{ 2s_1v_2^2}{2v_1^2} \\\\s_2 = \frac{s_1v_2^2}{v_1^2} \\\\s_2 = \frac{70\times 25^2}{15^2} \\\\s_2 = 194.44 \ m[/tex]
Thus, the braking distance of the road train is 194.44 m
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Convert 25 cm to km using the method of dimensional analysis
Answer:
0.00025km
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An atomic scients was studying an atom and through experimentation found that the total negative charge of the
area sounding the nucleus 9 Which statement correctly descnbes this atom?
This atom has time clouds
This atom has nine electrons
This atom has nine neutrons
This atom has the protons
this atom has nine electrons
Explanation:
since electrons are found outside the nucleus of an atom and they are negatively charged
Fluorescent lamp of 25W gives more light than the filament lamp of 50W. Why?
Answer:
Fluorescent lamp releases more light energy.
Explanation:
This is so because the fluorescent lamp releases more light energy and less heat energy than that of a filament lamp with the same rating.
Fluorescent lamp releases more light energy than that of filament lamp and also less heat energy than that of a filament lamp.
What is Power of fluorescent lamp and filament lamp?The filament and the fluorescent lamps are two different types of most commonly used light lamps. The filament lamps are the lamps which work on the phenomenon of incandescent whereas a high resistance filament is heated up in the lamp until it radiates visible light energy. Whereas, a fluorescent lamp is the lamp which works by ionizing a gas that emits photons or energy particles.
The fluorescent lamp releases more light energy and less heat energy than that of a typical filament lamp with the less power of 25W than 50W.
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A ball rolled at a speed of 3m/s for 2.5s. How far did it travel?
Answer:
7.5 m
Explanation:
speed = distance/time
=> speed × time = distance
=> (3 m/s) × (2.5 s) = distance
=> 7.5 m = distance
discuss one way in which global warming aggravates the effect of radiation
One way by which global warming aggravates the effect of radiation is through greenhouse effect
The combined effects of global warming and radiation is explained as follows.
Global warming is the gradual increase in the temperature of the Earth's surface (land), ocean and the atmosphere through the heat from the radiation of the sun.
One way by which global warming aggravates the effect of radiation is through greenhouse effect.
This occurs when the radiation from the sun is allowed to pass into the Earth's atmosphere but subsequent heat radiating from the Earth is prevented from escaping into the space.This greenhouse effect aggravates the effect of radiation.
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Please help me, I really need someone
Answer:
In plotting position versus time it can be seen that the green line represents a fixed position at the various times given - the other lines represent changing position with time
The (horizontal) green line describes an object that's not moving.
Whatever TIME you pick to look at the green line, its POSITION is always the same. This is a pretty good description of "not moving".
The other three lines all have different positions at different times, so they all describe motion.
A car accelerates by 4 m/s^2 and travels for 2.5 mins with an initial velocity of 20m/s. Find the final velocity.
Answer:
540m/s
Explanation:
v= u + at
u change t to seconds
why is electrostatic force able to act at a distance
In which group of elements does tellurium (Te) belong?
(1 point)
alkali metals
metalloids
lanthanides
transition metals
Answer:
metalloids
Explanation:
Periodic Table
A Periodic table is an arrangement of chemical elements in order of increasing atomic number.
Metalloids: Metalloids have properties that are midway between metals and non metals
Tellurium is a chemical element with symbol Te and atomic number 52. Classified as a metalloid, tellurium is a solid at room temperature.
Properties
Atomic Mass
127.6u
Oxidation States
+6, +4, -2
Year Discovered
1782
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what is the meaning of velocity?
Answer:
Velocity is quickness of motion or action. A synonym is celerity; a simpler word is speed. In physics, velocity specifically refers to the measurement of the rate and direction of change in position of an object.pls pls mark me branilest
Answer:
Velocity is defined as displacement travelled per unit time in a fixed direction. It is a vector quantity as it has both magnitude and fixed direction.
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Help due today as well
Answer: m/s north
explanation
Water does not run out of dropper unless the rubber-bulb is pressed. Why?
Answer:
The pressure inside the dropper is same as the atmospheric pressure when the rubber bulb is not pressed. ... But when we press the rubber bulb the pressure inside the dropper increases and hence the water flows out. Atmospheric pressure acting from outside the dropper balances the pressure exerted by water and water does not come out of a dropper. On pressing the dropper inside pressure of water becomes more than outside atmospheric pressure and water run out. When we press the bulb of a dropper with its nozzle kept in water, air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper.
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A shift inward of the production possibilities curve signifies that _
A. The demand for the products has increased, so the supply will increase
B. The available resources have increased, so potential production levels will increase
C. The available production resources have decreased, so potential production levels will decrease
D. The demand for the products has decreased so, the supply will decrease
Answer:
c
Explanation:
A shift inward of the production possibilities curve signifies that: C. The available production resources have decreased, so potential production levels will decrease.
A production possibilities curve (PPC) is also referred to as production possibilities frontier (PPF) and it can be defined as a curve that illustrates the maximum (best) combinations of two (2) products which can be produce in an economy if they both depend on these two (2) main factors;
Fixed technology. Fixed resources.Basically, the production possibilities curve (PPC) illustrates the maximum combinations of goods that are available with fixed technology and resources.
Furthermore, an inward shift of the production possibilities curve (PPC) signifies that the available resources used for production have decreased, so potential production levels would also decrease.
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The density of gold is 19.3 g cm³. What is the mass of a bar of gold in Kg that measures 6 cm x 4 cmx to 2 cm ?
solve
Answer: 0.9264 kg
Explanation: [I'll use "cc" for cubic centimeter, instead of cm^3.
The volume is 6cm*4cm*2cm = 48 cm^3 (cc).
Density of Au is 19.3 g/cc
Mass of gold = (48 cc)*(9.3 g/cc) = 926.4 grams Au
1 kg = 1,000 g
(926.4 grams Au)*(1 kg/1,000 g) = 0.9264 kg, 0.93 kg to 2 sig figs
At gold's current price of $57,500/kg, this bar is worth $53,268. Keep it hidden from your lab partner (and instructor).
The centrifugal force which tends to throw the electrons out it's orbit as stated with mass moving velocity in an orbit of radius is given as what?
Answer:
Mass, velocity, and radius are all related when you calculate centripetal force. ... The equation shows that if you increase mass or speed, you'll need a larger force; if you decrease the radius, you're dividing by a smaller number, so you'll also need a larger force.
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tides occurs in oceans but not in lakes.why?
Answer:
Explanation:
Tides occur in the ocean but nit in lakes because an ocean is a free flowing body of water that can travel a large area of the globe while a lake or pond only covers a small area of the earth so it is not affected by gravity as violently and in turn, prevents the formation of tides.
