Answer:
2.5 m
Explanation:
Billboard worker's weight = 800 N
Number of ropes = 2
Length of scaffold = 4 m
Weight of scaffold = 500 N
Tension present in rope = 550 N
The total torques will be
The worker is positioned at 2.5 m
The model of the atom has changed as scientists have gathered new evidence. Four models of the atom are shown below, but one imp
ortant model is missing.
An image at left with overlapping red and blue balls in the center with a circular fuzzy green cloud outside them. An image at center left with a purple ball in the center surrounded by overlapping concentric black ovals, each with a small green ball on each of the 6 ovals. An image at center right with a large black cross in a purple circle with a black line around the purple, with 10 small green balls dispersed within the purple circle.
Which atomic model is missing from this set?
Bohr’s model
Dalton’s model
Rutherford’s model
Thomson’s model
An image at left with overlapping red and blue balls in the center with a circular fuzzy green cloud outside them. An image at center left with a purple ball in the center surrounded by overlapping concentric black ovals, each with a small green ball on each of the 6 ovals. An image at center right with a large black cross in a purple circle with a black line around the purple, with 10 small green balls dispersed within the purple circle.
Which atomic model is missing from this set?
Bohr’s model
Dalton’s model
Rutherford’s model
Thomson’s model
2 answers:
Answer: Dalton’s model
Explanation:
The image provided depicts four atomic models, each marked with a letter:
W corresponds to the current widely accepted atomic model: a nucleus surrounded by an electron cloud, where the positions and orbits of electrons around the nucleus are defined by regions (linked to specific energy levels) where the probability of finding an electron is highest. It's key to note that this model was refined through the contributions of quantum physics by Louis de Broglie and Erwin Schrodinger.
X refers to Rutherford's model (developed after Thomson's model). Ernest Rutherford conducted experiments that confirmed Thomas's atomic theory. Yet, the results led him to discover that there was a core of charge in the atom (later termed the nucleus) surrounded by electrons. Thus, a new atomic model was introduced, showcasing a positively charged nucleus enveloped by negatively charged electrons, resembling the solar system.
Y denotes Thomson's model, often called the plum pudding model. This scientist identified that atoms include smaller charged particles, defined as electrons. At that point, without knowledge of the atomic nucleus, Thomson theorized that electrons floated in a positively charged substance that balanced the negative charge of the electrons, similar to raisins in pudding or bread.
Z symbolizes Bohr's model. Proposed by Danish physicist Niels Bohr after Rutherford's findings, this model incorporates Rutherford’s concept but adds that electrons travel in specific orbits around the nucleus at varying energy levels.
Hence, the absent model is Dalton's model, recognized as the first atomic model: the atom visualized as an indivisible, solid sphere. This was a generally accepted notion at the time, dating back to ancient Greek philosophy.
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assuming north-south is along the Y-axis and east-west along the X-axis
X = total X-displacement
from the graph, total displacement in the X-direction is computed as
X = 0 - 20 + 60 Cos45 + 0
X = 42.42 - 20
X = 22.42 m
Y = total Y-displacement
from the graph, total displacement in the Y-direction is computed as
Y = 40 + 0 + 60 Sin45 + 50
Y = 90 + 42.42
Y = 132.42 m
To calculate the magnitude of the net displacement vector, we apply the Pythagorean theorem, yielding
magnitude: Sqrt(X² + Y²) = Sqrt(22.42² + 132.42²) = 134.31 m
Direction: tan⁻¹(Y/X) = tan⁻¹(132.42/22.42) = 80.4 deg north of east
Answer:
The cooker receives an average energy transfer rate of 1.80 kW.
Explanation:
Given that,
Pressure of the boiling water = 300 kPa
Mass of water = 3 kg
Duration = 30 min
Dryness fraction of the water = 0.5
What is the average energy transfer rate to the cooker?
We know that,
The specific enthalpy of vapor at 300 kPa is
We need to determine the initial state enthalpy of water
We must find the enthalpy of water in the final state
Using the enthalpy formula
Insert the value into the formula
Next, we calculate the energy transfer rate to the cooker
Using the energy rate formula
Substituting the value into the formula
Therefore, the average energy transfer rate to the cooker stands at 1.80 kW.