science (Friction/Forces)
which option is correct?
Answer:
A
Explanation:
At constant speed, acceleration=0
From the formula, Fnet=ma (Resultant force= mass x acceleration), sub a=0
Fnet=0
Since the resultant force=0, the pushing force is equal to the frictional force
how do you calculate the numerical value of physical quantity
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.
a body is moving with uniform velocity of 15 m/s calculate its velocity after it travels 100m in 20 second
Since the body is moving with uniform velocity, its velocity after it travels 100 m in 20 s is 15 m/s.
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HELP!!!
Explain how magnetic potential energy can be transformed into kinetic energy.
Potential energy converts kinetic energy when the range is shifting from the S pole to the N pole.
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A dog runs from his home & goes 400 m around the block before reaching back home. What is the dog's total distance & displacement?
Distance: 0 m & displacement: 400m
Distance: 400 m & displacement:0m
Distance: Om & displacement:4 m
Distance: 4 m & displacement: Om
Answer:
A dog runs from his home & goes 400 m around the block before reaching back home. What is the dog's total distance & displacement?
Distance: 400 m & displacement:0m
Explanation:
Option B is the answer.
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what is momentum?????
Answer:
[tex]momentum \: is \: the \: force \: or \: speed \: of \: the \: movement \\ equation \\ momentum = mass \times change \: in \: velocity \\ thank \: you[/tex]
0.054x2.33x90............
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ram takes 2 minutes to cover a distance of 600 meter. calculate his speed
what is density?And It's SI unit.
Answer:
Density is defined as mass per unit volume. Hence its SI unit is: kg/m3
Explanation:
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The same 200 N force acts on an area greater than 2m2.
What happens to the pressure?
the pressure is (200 N)/(10 cm2)×(100 cm/M)2=200,000 pa
Two astronomers are viewing temperature data from each of the sun's layers, but the layers aren't identified. Describe one way the scientists can use temperature to identify which layer they are studying.(1 point) The highest temperatures are from the corona. The highest temperatures are from the corona. The lowest temperatures are from the photosphere. The lowest temperatures are from the photosphere. The lowest temperatures are from the core. The lowest temperatures are from the core. The highest temperatures are from the radiative zone.
Here we can study the different temperatures of each one of the layers of the sun.
We will find that the way that the scientist can identify which layer are they studying is "The lowest temperatures are from the photosphere."
A brief description of the temperature of each layer is:
Center of the sun: about 15 million K
Radiative Zone: Goes from 7 million K to 2 million K.
Convection Zone: goes from 2 million K to 5800K
Photosphere: Is in average 5800 K , but there are sunspots with lower temperatures, of around 3800 K.
Chromosphere: goes from 4300 K to 8300 K
Corona: Around 2 million K.
So now we can analyze each of the options to see which ones make sense.
A) The highest temperatures are from the corona.
This is false, we can see that in the center and in the radiative zone we have larger temperatures than in the corona.
B) The lowest temperatures are from the photosphere.
While on average the temperature of the photosphere is larger than the smaller temperature of the chromosphere, in the photosphere we have the sunspots, and there we have the smallest temperatures in the whole sun, so this is true.
C) The lowest temperatures are from the core (or center).
Clearly false, there we have the larger temperatures.
D) The highest temperatures are from the radiative zone.
Again false, the larger temperatures are in the center.
So the only true option is "The lowest temperatures are from the photosphere."
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Answer:
The lowest temperatures are from the photosphere
Explanation:
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A parachute is driven toward east direction with a speed of 20ms-1. A ball is thrown out with the speed of 4ms-1. What wil be the speed of the ball after it has been thrown out of parachute.
We have that the ball after it has been thrown out of parachute is
[tex]V_t=24ms^{-1}[/tex]
From the Question we are told
Parachute Speed [tex]v= 20ms^-1[/tex]
Ball Speed [tex]v= 4ms^{-1}[/tex]
Generally the equation for the resultant speed of the ball is mathematically given as
[tex]V_t=V_1+v_2\\\\v_t=20+4[/tex]
[tex]V_t=24ms^{-1}[/tex]
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In a molecule of lithium sulfide, there are two atoms of lithium and one atom of sulfur. Which statement about lithium sulfide is correct?(1 point)
The atoms in lithium sulfide are held together by bonds.
A molecular model of lithium sulfide would have two spheres.
The chemical formula for lithium sulfide is LiS2.
Both lithium and sulfur form positive ions.
Lithium sulfide is a compound and the atoms are held together by bonds.
What is a compound?Compound is defined as a chemical substance made up of identical molecules containing atoms from more than one type of chemical element.
Molecule consisting atoms of only one element is not called compound.It is transformed into new substances during chemical reactions. There are four major types of compounds depending on chemical bonding present in them.They are:
1)Molecular compounds where in atoms are joined by covalent bonds.
2) ionic compounds where atoms are joined by ionic bond.
3)Inter-metallic compounds where atoms are held by metallic bonds
4) co-ordination complexes where atoms are held by co-ordinate bonds.
They have a unique chemical structure held together by chemical bonds Compounds have different properties as those of elements because when a compound is formed the properties of the substance are totally altered.
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Compare and contrast scientific inquiry "skill and process".
Answer:
The inquiry process takes advantage of the natural human desire to make sense of the world... This attitude of curiosity permeates the inquiry process and is the fuel that allows it to continue. Process skills are not used for their own sake.
principle of simple Machine
Answer:
Effort×Effort distance = load× load distance
Answer:
Renaissance scientist
5) Two knights are jousting on horseback. It takes 2.2 seconds for the knights to meet in the middle
of the course and collide. If one knights horse ran at 6m/s and the other's horse at 9m/s, then
how far apart must they have been begin with?
Answer:
33m
Explanation:
Step 1: Whats going on?
We know that since they meet in the middle, and dont stop, that both knights take the same time to travel to the middle. This means that if they are traveling at a constant speed we can easily calculate the distance each travels
Step 2: Model it with Equations
General equation: V = D/t [m/s]
T = D1 + D2 = V1*t + V2*t = t * (v1 + v2)
Step 3: Sub in knowns
T = 2.2 s* (6m/s + 9m/s)
T = 33m
what is molecular formula give short answer
Explanation:
molecular formula consists of the chemical symbols for the constituent elements followed by numeric subscripts describing the number of atoms of each element present in the molecule. The empirical formula represents the simplest whole-integer ratio of atoms in a compound.
Answer:
The symbollic representation of a molecule of an element or a compound present in a molecule is called molecular formula.
For example: molecular formula of sodium chloride is NaCl.
What type of evidence is needed for a hypothesis to be supported or not supported?
O demonstrative evidence
O observational evidence
O physical evidence
O circumstantial evidence
Answer:
Answer in Observational evidence (b)
The evidence needed to formulate a hypothesis is observational evidence. From keen observations, we are formulating a scientific hypothesis.
What is hypothesis ?Hypothesis is a plausible scientific statement which predicts a process or result of an experiment based on observations. Hypothesis can be made from well established scientific records also.
Some are formulating hypothesis based on some intuitions, while some others are formulated based on inductions or deductions. An experiment starts from a clear cut hypothesis.
A hypothesis must be testable, falsifiable. A scientific hypothesis must be based on a strict observation and for a considerable time and the observations must support for the statement derived for the solution.
Hence, the evidence is needed for a or a hypothesis to be supported or not supported is observational evidence.
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2. What is an example of a question that cannot be solved using science?
Answer:
How did life begin on earth?
Explanation:
this is an example of a question that cannot be solved or why do we sleep too cannot be solved
Answer:
How did life on earth originate?
Explanation:
While there are many views on how life on earth started, especially from a religious stand point, scientists think this idea is "irrational". This is probably because it doesn't make sense how a higher power could create everything that we see on earth today from nothing. While they have tried to create simulations on how life could have possibly formed, they have gotten no answer.
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Explain how can a ripple tank be used to view wave pattern.
Answer:
when you push up and down the pencil right in the middle of the water tank. it will produce ripples. If seen at the perfect angle you will observe the waves
Explanation:
Prove that the acceleration due to gravity is independent to the mass of the falling body.
Answer:
½mv²=mgh
g=½(V²/h)
Explanation:
When an object is held at a height, it posses gravitational potential energy which is mgh, where m= mass, h=height, g=acceleration due gravity
When the object is dropped, the potential energy will be converted to kinetic energy which is ½mv², where V=velocity at which the object moves.
V=∆h/t, ∆h is change in height with respect to time.
½mv²=mgh
Mass cancel out,
g=v²/2h
This implies that g does not depend or is not affected by mass. Hence heavy object and light object will reach the ground at the same time when dropped from the same height. When air resistance is negligible.
5 sentences about the importance of investigatory project
Answer:
Student science investigatory projects provide students practical experience in using the scientific method and help stimulate their interest in scientific inquiry. Given the benefits society can realise from professional scientific inquiry, such goals in themselves have importance.
Hope it helps you.¿Qué ocurre como consecuencia de las corrientes de convección en la astenosfera?
Respuesta:En la astenosfera existen lentos movimientos de convección que explican la deriva continental. Además, el basalto de la astenosfera fluye por extrusión a lo largo de las dorsales oceánicas, lo cual hace que se renueve y expanda constantemente el fondo oceánico. :D
Name the component that the resistance decreases as the current increases.
Answer:
LDRs and thermistors
Light dependent resistors or LDRs are made of semiconductor material. Their resistance decreases as the light intensity increases. ... Their resistance decreases as the temperature increases.
PLEASE HELP
A 2.80 kg mass is dropped from a
height of 4.50 m. Find its kinetic
energy (KE) when it is 3.00 m
above the ground.
Answer:
41.16J
Explanation:
m =2.8 kg
h1 = 4.5 m
h2 = 3 m
PE at top = mgh1= 4.5mg
PE at 3 m = mgh2= 3mg
energy is conserved los in PE = gain in KE
KE at 3 m above the ground
= mg(4.5 - 3) J
= 2.8 kg*9.8m/s^2*1.5 m
= 41.16 joules
Answer: 42 m/s
Explanation:
m=2.8 kg , V1=0 m/s , h1=4.5 m , h2=3 m , V2=? m/s
E1 = E2 >>> K1 + U1 = K2 + U2
Kinetic Energy (KE) = K = [tex]\frac{1}{2}[/tex] m [tex]V^{2}[/tex] Potential Energy (PE) = U = mgh
[tex]\frac{1}{2}[/tex] m [tex]V1^{2}[/tex] + mg[tex]h_{1}[/tex] = K2 + mg[tex]h_{2}[/tex] >>> V1=0 >> K1=0 >>> K2 = -mgΔh
K2 = 2.8 kg × 10 m/s2 × 1.5 m = 42 m/s
What is the weight of a car that has a mass of 1250000 g
[tex]\\ \rm\hookrightarrow 1250000g=1250kg[/tex]
Mass=1250kgAcceleration=10m/s^2[tex]\\ \rm\hookrightarrow Force=Mass(Acceleration)[/tex]
[tex]\\ \rm\hookrightarrow Force=1250(10)[/tex]
[tex]\\ \rm\hookrightarrow Force=12500N[/tex]
The weight of the car that has a mass of 1250000 g would be 12262.5 N
What is Newton's second law?Newton's Second Law states that The resultant force acting on an object is proportional to the rate of change of momentum.The mathematical expression for Newton's second law is as follows
F = m*a
where F represents the force applied
m is the mass of the object and a is the acceleration of the object .
The major difference between the mass and the weight of an object is that mass of the object is constant throughout the universe while the way it can vary from the positional situation of the object in the universe for example the weight of the weight of the object in the earth would be different than the weight of the same object in some other planet for example The weight of an object on the Mars would be different than earth.
The weight of any object use the multiplication of the mass and the gravity of the respective planet in our case the weight is measured with respect to the gravity of the earth
Weight = Mass*(acceleration due to gravity)
W= m*g
The value of g for the earth is 9.81 m/s²
As per the given problem the car that has a mass of 1250000 g
1000 g = 1 kg
1250000 = 1250 kg
Weight = 1250*9.81
=12262.5 N
Thus ,the weight of the car that has a mass of 1250000 g would be 12262.5 N
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A girl walks 150 m from home to school in an easterly direction. She then turns and walks away 25 m to a shop what distance did the girl walk?
Answer:
175 miles
Explanation:
because when the girl walked from point A to B which is 150 miles and walks away 25 miles to a shop.
A carver begins work on a block of granite that has volume of 1000 cm3 and a density of 5 g/cm3. What is the mass of the block of granite?
Answer:
D (density) = M (mass) / V (volume)
M = D * V = 5 g / cm^3 * 1000 cm^3 = 5000 g
The mass of the block of granite is 5000 grams.
We know that density is defined as mass divided by volume. So, we can write the following equation:
Density = Mass / Volume
We are given that the density of the granite is 5 g/cm³ and the volume is 1000 cm³.
We can plug these values into the equation to solve for the mass:
5 g/cm³ = Mass / 1000 cm³
Mass = (5 g/cm³)(1000 cm³)
Mass = 5000 grams
1 cm³ of granite has a mass of 5 grams. So, a block of granite with a volume of 1000 cm³ will have a mass of 5000 grams.
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On his fishing trip Justin takes the boat 12 km south. The fish aren't biting so he goes 4 km North. He follows a school of fish 1 km further north.
What distance did he cover? What was his displacement?
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Answer:
Distance: 17 km
Displacement: 7 km
Explanation:
The distance is the total measure of how much he moved.
The displacement is the straight line between the star point and the end point
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.