Explanation:
Early Atomic theory
Although the idea of the atom was first suggested by Democritus in the fourth century BC, his suppositions were not useful in explaining chemical phenomena, because there was no experimental evidence to support them. It was not until the late 1700's that early chemists began to explain chemical behavior in terms of the atom. Joseph Priestly, Antoine Lavoisier, and others set the stage for the foundation of chemistry. They demonstrated that substances could combine to form new materials. It was the English chemist, John Dalton, who put the pieces of the puzzle together and developed an atomic theory in 1803.
Dalton's atomic theory contains five basic assumptions:
All matter consists of tiny particles called atoms. Dalton and others imagined the atoms that composed all matter as tiny, solid spheres in various stages of motion.
Atoms are indestructible and unchangeable. Atoms of an element cannot be created, destroyed, divided into smaller pieces, or transformed into atoms of another element. Dalton based this hypothesis on the law of conservation of mass as stated by Antoine Lavoisier and others around 1785.
Elements are characterized by the weight of their atoms. Dalton suggested that all atoms of the same element have identical weights. Therefore, every single atom of an element such as oxygen is identical to every other oxygen atom. However, atoms of different elements, such as oxygen and mercury, are different from each other.
In chemical reactions, atoms combine in small, whole-number ratios. Experiments that Dalton and others performed indicated that chemical reactions proceed according to atom to atom ratios which were precise and well-defined.
When elements react, their atoms may combine in more than one whole-number ratio. Dalton used this assumption to explain why the ratios of two elements in various compounds, such as oxygen and nitrogen in nitrogen oxides, differed by multiples of each other.
John Dalton's atomic theory was generally accepted because it explained the laws of conservation of mass, definite proportions, multiple proportions, and other observations. Although exceptions to Dalton's theory are now known, his theory has endured reasonably well, with modifications, throughout the years.
a. Opposite charges attract/repel each other, which means a Positive charge from a
proton/electron will attract/repel negative charge from an electron.
Answer:
Opposite charges attract each other, which means that a positive charge from a proton will attract negative charge from an electron.
Explanation:
Opposite charges attract because because their forced act in the same direction, which pulls them together. Protons are always positively charged subatomic particles and electrons are negatively charged subatomic particles. This attraction between the protons and electrons in atoms is what enables them to stay together and bond with other atoms.
Hope this helped!
Answer:
?
Explanation:
If the toy helicopter weighs 115 N and is hovering motionless in the air, which of these options MOST accurately describes the force that the helicopter's propeller must exert?
Answer:
If the helicopter is not moving, then it is not being accelerated.
By second Newton's law we have that:
F = m*a
Force equals mass times acceleration.
Then if we do not have acceleration, we have:
F = m*a = m*0 = 0.
Then the total force must be zero.
So if the gravitational force (pulling down) is 115N, then the force of the propeller must be such that:
Total force = F - 115N = 0
F = 115N
The force of the propeller must be also of 115N, but in the opposite direction.
What is the scientific method in physics ?
grade 9
1) Students watched a cartoon either alone or with others and then rated how funny they found the cartoon to be. Independent Variable: Dependent Variable:
Students watched a cartoon either alone or with others and then rated how funny they found the cartoon to be.
Independent Variable: student alone or with others
Dependent Variable: how funny student thought the cartoon was
Answer:
Independent Variable: Watching cartoon alone or with others
Dependent Variable: how funny they found the cartoon to be
Explanation:
A dependent variable is the variable being tested. The change in the value of dependent variable depends on the independent variable.
An independent variable is used to test the effects on dependent variable and its does not depend on any variable.
In the above example the dependent variable is how funny the cartoon was. This is being tested and it is tested by independent variable i.e. Students watching cartoon either alone or with others. So the cartoon is funny or not depends on watching cartoon alone or with friends.
A boat sails along the shore. To an observer, the boat appears to move at a speed of 11 m/s, and a man on the boat walking forward appears to have a speed of 12.4 m/s. How long does it take the man to move 6 m relative to the boat? A. 0.48 s B. 4.29 s C. 0.55 s D. 1.5 s
Answer:
B. 4.29s
Explanation:
If the man appears to move 12.4m/s when the boat appears to move 11m/s, it means that the man moves 1.4m on the boat (12.4-11=1.4). So if the man moves 1.4m per second then it will take him 6/1.4=4.29s to move 6 m relative to the boat.
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Extrinsic statements originate in a. Parents c. Teachers b. Society d. All of these Please select the best answer from the choices provided A B C D
Answer:
D all of these
Explanation:
Extrinsic statements originate in parents ,society and teachers. Option D is correct.
What is extrinsic motivation ?Extrinsic motivation is defined as conduct motivated by external incentives. Extrinsically driven people will continue to do something even if it isn't pleasurable or rewarding in and of itself.
These incentives might be monetary or intangible in nature, such as acclaim or renown. Extrinsic motivation is distinct from intrinsic motivation in that it is only motivated by external incentives.
Extrinsic statements originate in;
a. Parents
b. Society
c. Teachers.
Extrinsic statements originate in all of the above given option.
Hence, option D is correct.
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When a beam of light is incident on a surface, it delivers energy to the surface. The intensity of the beam is defined as the energy delivered per unit area per unit time.
What is the unit of intensity, expressed in SI base units?
Answer:
Kg
Explanation:
Given that the definition of intensity is:
The intensity of the beam is defined as the energy delivered per unit area per unit time. That is,
I =( E × t)/A
Which can expressed as
I = J/m^2/s
The S.I Units of
Energy is Joule = kgm^2s^-1
Area A = m^2
Time t = s
Intensity I = kgm^2s^-1 × m^-2 × s
Intensity I = kg
The cubic metres and seconds are cancelled out
Therefore, the S.I units of intensity is kg
Need helppp number 5
Answer:
1768 meters
Explanation:
Distance = speed x time.
(340 m/s) x (5.2 s) = 1768 m
what is eletro magnet
"Rate" is related to: Which is the correct answer A,B,C, or D A.volume B.percentage C.time D.distance
rate is primarily compared with time but can also be distance. Prime answer is C
Answer:
B. percentage
Explanation:
Rate, in the dictionary, means probability. When you use a percentage, you calculate either the amount of a certain thing out of the whole group, or the PROBABILITY of something.
What is the following correct way to write 2,330,000 in scientific notation
Answer:
The answer is 2.33 × 10 race to 6.
How many atoms of each element Are in the chemical formula NH4 NO3
Answer:
NITROGEN - 2
HYDROGEN- 4
OXYGEN- 3
Noah drops a rock with a density of 1.73 g/cm cubes into a pond. Will the rock float or sink? Explain your answer.
Answer:
The rock will sink.
Explanation:
The density of water is about 1 g/cm cubed, the rock being more dense will sink in water.
Answer:
Here is the answer.
Explanation:
prove that Force is equal to mass and acceleration
Potential energy is a type of energy. Which of the following bricks has the most potential energy? a two-pound brick that is three feet off the ground a two-pound brick that is five feet off the ground a four-pound brick that is three feet off the ground a four-pound brick that is five feet off the ground
Answer:
Hey there!
Potential Energy = mgh, (mass x gravitational acceleration x height)
Given that the gravitational acceleration is constant, we just have Potential Energy = mh
a. 2(3)=6
b. 2(5)=10
c. 4(3)=12
d. 4(5)=20
The four-pound brick that is five feet off the ground is the brick with the most potential energy.
Let me know if this helps :)
Scientists are told to doubt everything and not believe anything that is not provable. Is this a strength or weakness of science?
Please answer asappp :))
Tony completed a 720 km journey with an average speed of 90 km for the first 285 km he travel about an average speed of 95 km what was the average speed for the remaining journey
Answer:
87 km/h
Explanation:
720/90=8 8 Hours
285/95=3 3 hours
720-285=435 436 km left
8-3=5 5 hours left
435/5=87
87 km/H
Which of the following statements helps support the endosymbiotic theory?
Choose 1 answer:
(Choice A) A The Golgi body is a membrane-bound organelle within eukaryotes that was once a free-living prokaryote.
(Choice B) B If isolated from a eukaryotic cell, mitochondria can survive and reproduce on their own.
(Choice C) C Both mitochondria and chloroplasts have their own DNA that is different from the nuclear DNA of the larger host cell.
(Choice D) D The lysosome is a membrane-bound organelle within eukaryotes that was once a free-living prokaryote.
Answer:
C
Explanation:
Both mitochondria and chloroplasts have their own DNA that is different from the nuclear DNA of the larger host cell.
Mitochondrial DNA (mtDNA) and chloroplast DNA (cpDNA) actually more closely resemble the structure of prokaryotic DNA (circular) as compared to the structure of eukaryotic DNA (linear).
The endosymbiotic theory proposes that mitochondria and chloroplast were once independent prokaryotic organisms that survived endocytosis by an early eukaryotic cell.
The statement "both mitochondria and chloroplasts have their own DNA that is different from the nuclear DNA of the larger host cell" helps support the endosymbiotic theory (Option C).The lines of evidence that support the endosymbiotic theory include:
Both mitochondria and chloroplasts have their own circular DNA and divide by binary fission.Both mitochondria and chloroplasts have their own bacteria-like ribosomes (70 S).Both mitochondria and chloroplasts have a similar size as prokaryotic cells.In conclusion, the statement "both mitochondria and chloroplasts have their own DNA that is different from the nuclear DNA of the larger host cell" helps support the endosymbiotic theory (Option C).
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Alan rents a private jet for the weekend. He flies 400km south to New York then flies 821km south to North Carolina, then 1200km to Miami. What distance did he cover ? What was his displacement ?
Answer:
Distance = 2421 km
Displacement I'm not sure
I live in Asia
Bronchitis is a condition that’s characterized by coughing and the secretion of mucus. A person with bronchitis has inflamed airways, which makes it hard to breathe. Where does a bronchitis infection start?
Answer:the throat
Explanation:
Answer:
zszzzzzz
Explanation:
A forensic investigator is collecting hair samples from the victims and possible suspects of a violent attack. How many control
samples of full length scalp hairs and how many full length pubic hairs are collected for the control samples?
A)
25/10
B)
50/24
50/50
D)
100/50
Answer: B. 50/24
Explanation: just took the usatestprep
A uniform beam weighing 1 N is used as a metre rule. The beam is supported by a pivot
at the 30 cm mark. A 12 N weight is hung at the 0 cm mark and a 2 N weight is hung at the
60 cm mark as shown in Figure 5.19.
O cm
50 cm 60 cm
100 cm
수
► Figure 5.19
30 cm
mark 1 N
12 N
2 N
W
What is the weight W of a mass hung at the 100 cm mark in order to balance the beam?
Please help!
Answer:
then you solve two torque one is anticlockwise and one is clock wise toque 1=force*perpendicular distance is equal to torque 2= force* perpendicular distance so tau = torque 1+ torque 2and give your answer
Answer:
W = 4 N (to balance the beam)
Explanation:
take moment at support Δ
∑M at Δ = 0 (note: clockwise is + and counter clockwise is - )
0 = W(100 - 30) + 2(60-30) + 1(50-30) - 12(30)
0 = W70 + 2(30) + 1(20) - 360
0 = W70 + 60 + 20 - 360
0 = W70 - 280
280 = W70
W = 280 / 70
W = 4 N (to balance the beam)
to take the reaction at support Δ
Δ = 12 + 1 + 2 + 4
Δ = 19 N
proof that W = 4
∑M at 12N = 0
0 = 19(30) - 1(50) - 2(60) - W(100)
0 = 570 - 50 - 120 - 100W
100W = 400
W = 400 / 100
W = 4 N -------- ok
The cells in your nose that detect smell are a type of what
Answer: chemoreceptor apex!!!!!!!
Explanation:
A pesticide kills insects by disabling the ribosomes in their cells.
Which of the following functions would be most immediately inhibited in the insects' cells?
Choose 1 answer:
(Choice A) A Protein synthesis
(Choice B) B DNA replication
(Choice C) C Photosynthesis
(Choice D) D Cell division
Answer:
protein synthesis
Explanation:
A pesticide kills insects by disabling the ribosomes in their cells. The function that would be most immediately in the insects' cells is protein synthesis. The correct option is A.
What are pesticides?Pesticides are the chemicals that are used to kill insects and other microbes that infect the crops and other things. Pesticides are very harmful for health of other animals and humans. They also cause disabilities in birds which eat the insects killed by pesticides.
Protein synthesis is a process of synthesizing protein in the cell. This process done by cell organelles and DNA and RNA. Pesticides degenerate the process of protein synthesis in insects, they eventually die due to no working of cell.
Thus, the correct option is A Protein synthesis.
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If a truck travels 100 miles in 2 hours, what is its speed? (Hint: Do not forget to write the unit).
Submit
The truck is going at a speed of 50 MPH.
Which of following answer choices properly match the cell structure and function depicted by this image?
Choose 1 answer:
(Choice A)
A
Nucleus — storage of genetic material
(Choice B)
B
Golgi body — receiving, sorting, and packaging cell materials for transport
(Choice C)
C
Golgi body — breaking down sugar molecules and converting their energy to ATP for the cell
(Choice D)
D
Lysosome — receiving, sorting, and packaging cell materials for transport
Answer:
B
Golgi body — receiving, sorting, and packaging cell materials for transport
Explanation:
The Golgi body is responsible for receiving, classifying, and packing cell components for transportation in a manner that is consistent with the cell form and function are shown in this figure. Option B is correct.
What are Golgi bodies?The majority of eukaryotic cells' cytoplasm contains a combination of vesicles and folded membranes that are used for secretion and intracellular transport known as the Golgi bodies.
Golgi body — receiving, sorting, and packaging cell materials for transport properly match the cell structure and function depicted by this image.
This graphic accurately depicts the cell structure and function of the Golgi body, which receives, sorts, and packages cell components for transit.
Hence, option B is correct.
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a parking lot is going to be 60m wide and 240m long which dimensions could be used please please help
Answer: The area of the parking lot is 14,400 meters squared.
Explanation:
We have the dimensions of the parking lot.
60m by 240m
The units used here are meters.
Now, if we want to know the area of the parking lot is equal to the product between the length and the width:
A = 60m*240m = 14,400 m^2
The area of the parking lot is 14,400 meters squared.
Answer:
A = 20x80
Explanation: DID IT ON APEX
Chich expression correctly describes force using Sl units
O A. 1 N = 1 kg-m/s2
B. 1 N = 1 kg.m/s
C. 1 J = 1 kg-m/s?
D. 1 J = 1 kg m/s
Answer:1 N = 1 kg·m/s2
Explanation:
a force of 5 N extends a spring of natural length 0.5m by 0.01, what will be the length of the spring when the applied force is 20 N
Answer:
L_new =L+x^2 = L_new = 0.54_m.
Explanation:
Given data:
Force in the first case,
F_1 = 5N
Force in the second case,
F_2 = 20 N
Natural length of spring,
L= 0.5
Extension in the first case,
x_1 = 0.01m
Let the force constant of the spring be k.
Thus,
F_1=kx_1
5 = k × 0.01
⇒ k = 500 N/m.
The extension in the spring in the second case can be given as,
F_2=kx_2
20 = 500x_2
⇒ x_2 = 0.04 m.
Thus, the effective length of the spring would be,
L_new =L+x^2
L_new = 0.5+0.04
L_new = 0.54_m.
How do you close a ripped sandwhich bag?