A car engine burns gas at 495 K and exhausts to the air at 293 K. What is the highest possible efficiency it could have?
(NO UNIT)
Answers
Answer:
59.19%
Explanation:
Step 1:
Data obtained from the question. This include the following:
Input temperature = 495 K.
Output temperature = 293 K.
Efficiency =..?
Step 2:
Determination of the efficiency of the engine.
Efficiency is simply defined as the ratio of output to input times 100. Mathematically, it is expressed as:
Efficiency = output /input x 100
With the above formula, we can calculate the efficiency of the engine as follow:
Input temperature = 495 K.
Output temperature = 293 K.
Efficiency =..?
Efficiency = output /input x 100
Efficiency = 293/495 x 100
Efficiency = 59.19%
Therefore, the efficiency of the engine is 59.19%
Answer:
0.41
Explanation:
Trust me bro
Related Questions
a man with mass 81 kg lies on the floor. what is the normal force on the man?
Answers
Answer:
Forces come in pairs, so the force of gravity (9.8 N) with the mans weight (794N) on the earth is counteracted with the normal force ( the force of the earth back on the man) which is the same
Explanation:
Forces are available in pairs, so the force of gravity (nine.8 N) with the man's weight (794N) on the planet is counteracted with the everyday force ( the pressure of the earth again on the man) that's identical.
What is the gravitational force?Gravitational force is a pressure that draws any items with mass. We name the gravitational force appealing as it constantly attempts to tug loads collectively, it never pushes them apart. In reality, every item, together with you, is pulling on each other objects inside the complete universe.
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PLEASEEE HELP, thank you :)
Answers
Answer:
The answer is B.
Explanation:
Given that the current (Ampere) in a series circuit is same so we can ignore it. We can assume that the total voltage is 60V and all the 3 resistance are different, 20Ω, 40Ω and 60Ω. So first, we have to find the total resistance by adding :
Total resistance = 20Ω + 40Ω + 60Ω
= 120Ω
Next, we have to find out that 1Ω is equal to how many voltage by dividing :
120Ω = 60V
1Ω = 60V ÷ 120
1Ω = 0.5V
Lastly, we have to calculate the voltage at R1 so we have to multiply by 20 (R1) :
1Ω = 0.5V
20Ω = 0.5V × 20
20Ω = 10V
How is a less-intense wave different from a more-intense wave?
It has fewer decibels.
O It has a higher pitch.
O It has more volume.
It has more energy.
Answers
Answer: It has fewer decibels.
Explanation:
In a sound-wave, the intensity is defined as the power carried by the wave. The decibel is a measure of the ratio between two quantities. And in acoustics is used as the unit of the sound pressure level, which is related to the intensity of the wave, then:
As the intensity increases, we also should notice an increase in the decibels.
How is a less-intense wave different from a more-intense wave?
The less-intense wave has fewer decibels.
Answer:
It has fewer decibels.
Explanation:
Joan makes the device shown in her science class.
An illustration with a battery and ends labeled positive and negative. A wire is connected to the positive end of the battery and curls around an iron nail and connects back with the negative side of the battery.
What would happen to the magnetic field if she connects the battery in the opposite direction?
The field would stop.
The field would get stronger.
The field would reverse its poles.
The field would get weaker.
Answers
Answer:
The field would reverse its poles.
Explanation:
The current flow will reverse directions which will reverse the poles in the magnetic field created around the iron nail.
If she connects the battery in the opposite direction, the magnetic field would reverse its poles.
What is magnetic field?The magnetic field is the region of space where an object experiences the magnetic force and obtain magnetic properties.
A wire is connected to the positive end of the battery and curls around an iron nail and connects back with the negative side of the battery. This arrangement will let the current flow from the positive end of the battery towards the negative terminal of the battery.
If the battery is connected in the opposite direction, the current will flow from negative to positive terminal.
Therefore, If she connects the battery in the opposite direction, the magnetic field would reverse its poles.
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(I) A hiker determines the length of a lake by listening for the echo of her shout reflected by a cliff at the far end of the lake. She hears the echo 2.5 s after shouting. Estimate the length of the lake.
Answers
Answer:
425 m
Explanation:
From the question,
v = 2x/t.................... Equation 1
Where v = speed of sound in air, x = Length of the lake, t = time.
make x the subject of the equation
x = vt/2............... Equation 2
Given: t = 2.5 s
Constant: v = 340 m/s.
Substitute these values into equation 2
x = 340(2.5)/2
x = 425 m.
Hence the length of the lake is 425 m
Allocate birr 5000 among the three workers in the ratio 1/3 :1/6 and 5/12.
Answers
Answer:
1666.7 ETB (birr)
833.3 ETB (birr)
2083.3 ETB (birr)
Explanation:
The first worker
5000*1/3=1666.7
The second worker
5000*1/6=833.3
The third worker
5000*5/12=2083.3
Hope this helps :) ❤❤❤
explain why energy is important to us?
Answers
Answer:
we need it to work and without it we dont have strength to do anything
Answer:
energy is important to all living organisms. energy for producers comes from the sun, and energy for consumers comes from other living organisms. the abundance of energy available for organisms impacts the population.
Thurst exerted by an object of area20m² experiencing pressure 150 Nm‐² is ________
Answers
Answer:
3000 N
Explanation:
as we know that
pressure=force/area
so force=thurst
pressure=thurst/area
thyrst=pressure*area
pressure=150 Nm^-2
area=20m^2
so thurst=150*20=3000 N or 3*10^3 N
an elastic cord 61 cm long when a weight of 75N hangs from it, but 85cm when a weight of 210N hangs from it. what is the spring constant of the cord
Answers
Answer:
560 N/m
Explanation:
F = kx
75 N = k (0.61 m − L)
210 N = k (0.85 m − L)
Divide the equations:
2.8 = (0.85 − L) / (0.61 − L)
2.8 (0.61 − L) = 0.85 − L
1.708 − 2.8L = 0.85 − L
0.858 = 1.8L
L = 0.477
Plug into either equation and find k.
75 = k (0.61 − 0.477)
k = 562.5
Rounded to two significant figures, k = 560 N/m.
A 115 kg hockey player, Adam, is skating east whenever he tackles a 133 kg player, Bob, skating west at -1.59 m/s. Afterwards, they move together at .250 m/s east. What was Adam's velocity before the collision? (Unit = m/s)
Answers
Answer:
2.38 m/s
Explanation:
Momentum is conserved:
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
After the collision, they move at the same speed, so v₁ = v₂ = v.
m₁u₁ + m₂u₂ = (m₁ + m₂) v
Plugging in numbers:
(115 kg) u₁ + (133 kg) (-1.59 m/s) = (115 kg + 133 kg) (0.250 m/s)
u₁ = 2.38 m/s
A calculator displays a result such as 1,365 248 0 107 kg. The estimated uncertainty in the result is 2%. How many digits should you include as significant when you write the result? Choose one:
1) zero,
2) one,
3) two,
4) three,
5) four
6) five,
7) the number cannot be determined.
Answers
Answer:
4) three
Explanation:
Assuming you mean 1.365248×10⁷, 2% of that is:
0.02 (1.365248×10⁷) = 0.027305×10⁷
So the number is:
1.365248×10⁷ ± 0.027305×10⁷
We need to round this number so that there is uncertainty only in the last digit.
1.37×10⁷ ± 0.03×10⁷
There are three significant figures in 1.37.
Explain length and time dilation and give an example of when each is observed.
Answers
Answer:
Length contraction
A moving object traveling at a velocity approaching the speed of light will appear to be shorter or to have undergone contraction.
The proportion by which the object is observed to have contracted is given by Lorentz transformation as follows;
[tex]L = L_{0}\cdot \sqrt{1 -\dfrac{v^{2}}{c^{2}}}= \dfrac{L_{0}}{\gamma }[/tex]
Time dilation
As the relative speed of motion of an object approaches the speed of light, the clock in the frame in motion will be observed to be moving slowly or dilated in a proportion given by Lorentz transformation as follows;
[tex]T = \dfrac{T_{0}}{\sqrt{1 -\dfrac{v^{2}}{c^{2}}}}[/tex]
Explanation:
Example of length contraction example
Two square boxes of side length L which are travelling at a velocity of 0.9 × c, are going to arranged in a single box of side side length L according to length contraction Lorentz transformation, to stationary observer we have
[tex]2 \times L\cdot \sqrt{1 -\dfrac{(0.9 \cdot c)^{2}}{c^{2}}}= 0.8 \cdot L[/tex]
To the stationary observer, the 2 boxes of length L will fit side by side in the single box of length L, while to those on the space ship carrying the boxes, the size of the single box is [tex]L\cdot \sqrt{1 -\dfrac{(0.9 \cdot c)^{2}}{c^{2}}}= 0.4 \cdot L[/tex], which will not contain half of one box
Example of of time dilation example
Twin A of two twins, twin A and B went on a space journey at the speed of 0.87·c for 5 years, the number of years past for twin B when they meet again will be [tex]T = \dfrac{5}{\sqrt{1 -\dfrac{(0.87\cdot c)^{2}}{c^{2}}}} = 10.14 \ years[/tex]
A submarine emerges 1/9 of its volume when it partially floats on the sea surface. For make it completely submerge it is necessary to allow a volume of 50,000 [L] to enter of sea water whose density is 1,026 [g / cm3]. What is the weight of the submarine?
Answers
Answer:
4,524,660 N
Explanation:
Assuming the submarine's density is uniform, 1/9th of the submarine's mass is equal to the mass of the displaced water.
m/9 = (1026 kg/m³) (50 m³)
m = 461,700 kg
mg = 4,524,660 N
A 1,383 kg purple car is driving southbound on a road and collides with a 1,827 kg orange car, that was traveling 31.87 m/s eastbound. The two cars collide and stick, sliding 14.54 meters before coming to rest. What was the initial velocity of the two-car system just after the collision? Take the coefficient of friction to be 0.463, and the acceleration due to gravity to be 9.8 m/s2. Answer to two decimal places.
Answers
Answer:
Explanation:
We shall apply work energy theorem to calculate the initial velocity just after the collision .
Their kinetic energy will be equal to work done by friction .
force of friction = μ mg , where μ is coefficient of friction , m is total mass and g is acceleration due to gravity
force = .463 x 3210 x 9.8
= 14565.05 N
work done = force x displacement
= 14565.05 x 14.54 = 211775.88 J
now applying work energy theorem
1/2 m v² = 211775.88 , m is composite mass , v is velocity just after the collision
.5 x 3210 x v² = 211775.88
v² = 131.94
v 11.48 m /s
In the school cafeteria, a trouble-making child blows a 12.0 g spitball through a 25.0 cm straw. The force (F) in Newtons, of his breath as a function of the distance along the straw (x) in meters, can be modeled as a linearly decreasing function for the first half of the straw, followed by a constant force through the rest of the straw. The force decreases by half along the first half of the straw. Assume there is negligible friction and the straw is held horizontally.
(a) Sketch a plot of the force of his breath as a function of position along the straw, labeling the force at x = 0 as F0.
(b) If the spitball begins from rest and leaves the straw with a speed of 16 m/s, how much work is done on the spitball?
(c) What is the maximum force F0, that acts on the spitball?
Answers
Answer:
A.) Find the attached file
B.) 1.536 J
C.) 123N
Explanation:
Given that the force (F) in Newtons, of his breath as a function of the distance along the straw (x) in meters, can be modeled as a linearly decreasing function for the first half of the straw,
Half of the straw = 12.5 cm
Let Force F = dependent variable
And distance x = independent variable
A.) Find the attached file for the graph.
Sinnce the force decreases by half along the first half of the straw. Assume there is negligible friction and the straw is held horizontally
B.) Given that the mass M = 12g = 12/1000 = 0.012kg
And Velocity V = 16m/s
The workdone = the kinetic energy of the split ball
WD = 1/2mv^2
Substitutes m and V into the formula
WD = 1/2 × 0.012 × 16^2
WD = 1.536 Joule
C.) The maximum force acts on the spit ball will be at maximum kinetic energy.
Since work done = force × distance
Where distance = 12.5 cm
F × S = 1/2mv^2
Substitutes all the parameters
F × 0.0125 = 1.536
Make F the subject of formula
F = 1.536/0.0125
F = 122.88 N
The maximum force F0, that acts on the spitball is therefore equal to 123 N approximately.
We have that for the Question "(a) Sketch a plot of the force of his breath as a function of position along the straw, labeling the force at x = 0 as F0.
(b) If the spitball begins from rest and leaves the straw with a speed of 16 m/s, how much work is done on the spitball?
(c) What is the maximum force F0, that acts on the spitball?"
It can be said that
a) The sketch is attachedb) The workdone = [tex]1.536J[/tex]c) Maximum force = [tex]6.4N[/tex]From the question we are told
mass of spitball = 12g through a 25.0 cm straw
Generally the equation for workdone is mathematically given as
[tex]= \frac{1}{2}mv^2 - 0\\\\= \frac{1}{2} * 12*10^{-3} * 16^2\\\\= 1.536J[/tex]
Maximum force
[tex]w = \frac{1}{2}*\frac{x_0}{2}*\frac{F_0}{2} + x_0*\frac{F_0}{2}\\\\w = \frac{5}{8}x_0F_0[/tex]
Therefore,
[tex]F_0 = \frac{8w}{5x_0}\\\\F_0 = \frac{8*1.536}{5*25*10^[-2]}\\\\F_0 = 6.4N[/tex]
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Sally is concerned about the X-ray images her dentist plans to take of her teeth. She has read that X-rays can cause tissue effects, such as skin reddening and hair loss. Which statement would best inform Sally of the level of risk
Answers
Answer:
B. The dentist uses X-ray radiography, which takes too short a time to cause those problems.
Explanation:
The statement B would best inform Sally of the level of risk. The dentist uses X-ray radiography, which takes too short a time to cause those problems and risk.
What is X-ray imaging?X-ray imaging provides images of human internal organs. The photos depict your body parts in various colors of black and white.
Because various tissues absorb varying quantities of radiation, this is the case. Because calcium absorbs the most x-rays, bones appear white.
When X-ray radiation passes into our bodies, it damages molecular structures and may cause injury.
Human cells are damaged by extremely high doses of radiation, as indicated by skin burns, hair loss, and an increased risk of cancer.
Sally is concerned about the X-ray images her dentist plans to take of her teeth. She has read that X-rays can cause tissue effects, such as skin reddening and hair loss.
The statement B would best inform Sally about the level of risk. The dentist uses X-ray radiography, which takes too short a time to cause those problems and risk.
Hence, statement B would best inform Sally about the level of risk.
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Which of the following would cause the force of static friction to increase?
Answers
Answer:
Answer B) An increase in [tex]\mu_S[/tex]
Explanation:
Since we are talking about the force of static friction, due to its definition as the product between the normal force to the surface times the coefficient of static friction, the only two ways such force could increase is due to an increase in the normal force, or an increase in the coefficient of static friction [tex]\mu_S[/tex].
So the only valid answer is answer B)
Which of these are scientific questions? Check all that apply. How will climate change affect forests? Which planet is the prettiest? How did life on Earth begin? Why did dinosaurs go extinct? Which volcano is the most amazing?
Answers
Answer:
The scientific questions here are:
a) How will climate change affect forests
b) How did life on Earth begin
c) Why did dinosaurs go extinct
Explanation:
Scientific question are logical quantifiable questions, whose answers can be measured. A good scientific question must have answers that can be tested by a carefully designed experiment or measurement. Some qualities like "prettiest" and "amazing" cannot be tested for nor are they measurable, and hence, they do not make a testable component of good scientific question.
A ball is projected at an angle of elevation of 60 ° with an initial velocity of 120m/s.calculate
1) The time taken to get to the maximum height
ii) the time of flight
Answers
Explanation:
It is given that,
The angle of projection is 60 degrees
Initial velocity of the ball is 120 m/s
We need to find the time taken to get to the maximum height and the time of flight.
Time taken to reach the maximum height is given by :
[tex]T=\dfrac{u^2\sin^2\theta}{2g}[/tex]
g is acceleration due to gravity
[tex]T=\dfrac{(120)^2\times \sin^2(60)}{2\times 10}\\\\T=540\ s[/tex]
(ii) Time of flight,
[tex]t=\dfrac{2u\sin\theta}{g}[/tex]
So,
[tex]t=\dfrac{2\times 120\times \sin(60)}{10}\\\\t=20.78\ s[/tex]
Hence, this is the required solution.
Neglecting air resistance, the distance s(t) in feet traveled by a freely falling object is given by the function s(t)=16t2, where t is time in seconds. The height of a certain tower is 840 feet. How long would it take an object to fall to the ground from the top of the building?
Answers
Answer:
t=7.25 sec
Explanation:
840=16t'2,
A car travels 18 km / h to the northwest. What is the speed of this car seen from another car going south at 60 km / h?
Answers
Answer:
73.8 km/h
Explanation:
The velocity of object A relative to object B is:
v = va − vb
Let's say east is +x and north is +y, and angles are measured from +x.
The velocity of the first car in the x direction is:
18 km/h cos 135° = -9√2 km/h
The velocity of the first car in the y direction is:
18 km/h sin 135° = 9√2 km/h
The velocity of the second car in the x direction is:
60 km/h cos 270° = 0 km/h
The velocity of the second car in the y direction is:
60 km/h sin 270° = -60 km/h
The relative velocity in the x direction is:
vₓ = -9√2 km/h − 0 km/h = -9√2 km/h ≈ -12.7 km/h
The relative velocity in the y direction is:
vᵧ = 9√2 km/h − (-60 km/h) = 9√2+60 km/h ≈ 72.7 km/h
The speed, or magnitude of the velocity, is:
v = √(vₓ² + vᵧ²)
v = √((-12.7 km/h)² + (72.7 km/h)²)
v ≈ 73.8 km/h
The robot HooRU is lost in space, floating around aimlessly, and radiates heat into the depths of the cosmos at the rate of 13.5 W. HooRU's surface area is 1.51 m^2 and the emissivity of its surface is 0.209. Ignore the radiation HooRU absorbs from the cold universe. What is HooRU's temperature?
Answers
Answer:
165.73 K
Explanation:
The computation of HooRU's temperature is shown below:-
As per the stefan's law, the power radiated by black body radiations which is
[tex]P = eA\sigma T^4[/tex]
where
A indicates surface area
e indicates emissitivity
T indicates temperature
now, we will put the values in the above equation
[tex]13.5 = 0.209 \times 1.51 \times \sigma \times T^4[/tex]
After solving the above equation we will get temperature which results
= 165.73 K
Therefore for computing the HooRU's temperature we simply applied the above formula.
Bumper car A (331 kg) moving east at 3.87 m/s hit stationary car B (208 kg). After, the car A moves .88 m/s east. What is the velocity of car B?
Answers
Answer:
Ub = 221.99m/s
Explanation:
(Ma x Ua)+(Mb x Ub) = (Ma + Mb)V
(331 x 3.87)+(208 x Ub) = (331 + 208)88
(1257.8) + (208 x Ub) = 47432
(208 x Ub) = 47432 - 1257.8
(208 x Ub) = 46174.2
Ub = 46174.2/208 = 221.99m/s
Ub = 221.99m/s
Answer:
4.75
Explanation:
M1V1 + M2V2 = M1V3 + M2V4
[(331*3.87) , 90°] + 0 = [(331*0.888) , 90°] + M2V4
M2V4 = 987.042 , 90°
divide through by M2
V4 = 4.75 m/s east
The three-dimensional arrangement of electron groups around the central atom is called ____.
A. Election-pair repulsion
B. Electronegativity
C. Geometric design
D. Electron-group geometry
Answers
Answer:
D. Electron - group geometry
Explanation:
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When you urinate, you increase pressure in your bladder to produce the flow. For an elephant, gravity does the work. An elephant urinates at a remarkable rate of 0.0060 m3 (a bit over a gallon and a half) per second. Assume that the urine exits 1.0 m below the bladder and passes through the urethra, which we can model as a tube of diameter 8.0 cm and length 1.2 m. Assume that urine has the same density as water, and that viscosity can be ignored for this flow.
1) What is the speed of the flow? It is 1.2 m/s
2) If we assume that the liquid is at rest in the bladder (a reasonable assumption) and that the pressure where the urine exits is equal to atmospheric pressure, what does Bernoulli's equation give for the pressure in the bladder? (In fact, the pressure is higher than this; other factors are at work. But you can see that no increase in bladder pressure is needed!)
Answers
Answer:
1) v = 1.19 m / s , 2) P₁ = 9.308 10⁴ Pa
Explanation:
In this exercise we will simulate the emission of urine as a fluid mechanics system
1) they indicate the urine flow rate Q = 0.0060 m³ / s, they also give the diameter of the tube 8.0 cm, they ask us the speed.
Let's use the continuity equation
Q = v A
The area of a cycling tube is
A = π r² = π d² / 4
we substitute
Q = v π d² / 4
v = 4Q / π d²
let's calculate
v = 4 0.006 / (π 0.08²)
v = 1.19 m / s
2) they ask to find the pressure in the bladder, for this we use the Bernoulli equation, where the index is for the bladder and the index 2 is for the exit point
P₁ + ½ ρ v₁² + ρ g y₁ = P₂ + ½ ρ v₂² + ρ g y₂
in the exercise it indicates that the outlet pressure is equal to the atmospheric pressure P₂ = 1,013 10⁵ Pa, the velocity of the liquid in the bladder is v₁ = 0 and the height difference 1.0 m
P₁ = P₂ + ½ ρ v₂² + ρ g (y₂-y₁)
let's calculate
P₁ = 1.013₁ 10⁵⁵ + ½ 1000 1.19 + 1000 9.8 (0-1)
P₁ = 1.013 105 + 595 - 9800
P₁ = 9.308 10⁴ Pa
A vat of nitrogen at its boiling point (-196 degrees C) absorbs 384000 J of heat. How much mass of nitrogen burns off? (Unit = kg)
Answers
Answer:
1.92 kg of nitrogen.
Explanation:
The following data were obtained from the question:
Heat absorbed (Q) = 384000 J
Note: Heat of vaporisation (ΔHv) of nitrogen = 5600 J/mol
Next, we shall determine the number of mole of nitrogen that absorbed 384000 J.
This is illustrated below:
Q = mol·ΔHv
384000 = mole of N2 x 5600
Divide both side by 5600
Mole of N2 = 384000/5600
Mole of N2 = 68.57 moles
Next, we shall convert 68.57 moles of nitrogen, N2 to grams.
This can be obtained as follow:
Molar mass of N2 = 2 x 14 = 28 g/mol.
Mole of N2 = 68.57 moles.
Mass of N2 =..?
Mole = mass /molar mass
68.57 = mass of N2 /28
Cross multiply
Mass of N2 = 68.57 x 28
Mass of N2 = 1919.96 g
Finally, we shall convert 1919.96 g to kilograms.
This can be achieved as shown below:
1000g = 1 kg
Therefore,
1919.96 g = 1919.96/1000 = 1.92 kg.
Therefore, 1.92 kg of nitrogen were burned off.
Answer:
Explanation:
i cheat on Acellus cause I dont care about school. If i did I would be going to public school... Im never gonna use this info in my life so I dont bother learning it.
A student environmental group is creating a campaign for locally sourced energy resources.What would be best for them to feature in their campaign?a coal mine located in their countya farmer with a field of solar panelsa company building a gas pipeline through the towna rancher drilling for oil in a horse pasture
Answers
Answer:
A farmer with a field of solar panels.
Explanation:
The closest to a locally sources energy would have been
A coal mine located in their county.
But coal as an energy source is not environmentally friendly due to carbon emission, and should not be what the group should advocate for.
The best bet for them is
A farmer with a field of solar panels.
As solar panels are a source of green energy and green energy is what the environmental group should often and always advocate for
250 mL 0.1 M HCl solution is mixed with 250 mL
0.2 M NaOH. The concentration of OH- in the
mixture is
Answers
Answer:
The concentration of OH⁻ in the mixture is 0.05 M
Explanation:
The reaction of neutralization between HCl and NaOH is the following:
H⁺(aq) + OH⁻(aq) ⇄ H₂O(l)
The number of moles of HCl is:
[tex] n_{HCl} = C*V = 0.1 mol/L*0.250L = 0.025 moles [/tex]
Similarly, the number of moles of NaOH is:
[tex] n_{NaOH} = C*V = 0.2 mol/L*0.250L = 0.05 moles [/tex]
Now, from the reaction of HCl and NaOH we have the following number of moles of NaOH remaining:
[tex] n_{NaOH} = 0.05 moles - 0.025 moles = 0.025 moles [/tex]
Finally, the concentration of OH⁻ in the mixture is:
[tex]C =\frac{n_{NaOH}}{V_{T}}=\frac{0.025 moles}{0.250*2 L} = 0.05 moles/L[/tex]
Therefore, the concentration of OH⁻ in the mixture is 0.05 M.
I hope it helps you!
a body weights 28N at a height of 3200km from the earth surface.What will be the gravitational force on that body if its lies on the earth surface.
Answers
Answer:
The object would weight 63 N on the Earth surface
Explanation:
We can use the general expression for the gravitational force between two objects to solve this problem, considering that in both cases, the mass of the Earth is the same. Notice as well that we know the gravitational force (weight) of the object at 3200 km from the Earth surface, which is (3200 + 6400 = 9600 km) from the center of the Earth:
[tex]F_G=G\,\frac{M_E\,m}{d^2} \\28\,\,N=G\,\frac{M_E\,m}{9600000^2}[/tex]
Now, if the body is on the surface of the Earth, its weight (w) would be:
[tex]F_G=G\,\frac{M_E\,m}{d^2} \\w=G\,\frac{M_E\,m}{6400000^2}[/tex]
Now we can divide term by term the two equations above, to cancel out common factors and end up with a simple proportion:
[tex]\frac{w}{28} =\frac{9600000^2}{6400000^2} \\\frac{w}{28} =\frac{9}{4} \\\\ \\w=\frac{9\,*\,28}{4}\,\,\,N\\w=63\,\,N \\[/tex]
Let us treat a helicopter rotor blade as a long thin
rod, as shown in Fig. 8–49. (a) If each of the three rotor
helicopter blades is 3.75 m long and has a mass of 135 kg,
calculate the moment of inertia of the three rotor blades
about the axis of rotation. (b) How much torque must the
motor apply to bring the blades from rest up to a speed
of 6.0 rev/s in 8.0 s?
Rotor
Answers
Answer:
(a) 1900 kg m²
(b) 8950 Nm
Explanation:
(a) The moment of inertia of a rod about its end is I = ⅓mL².
For 3 rods of mass m = 135 kg and length L = 3.75 m, the total moment of inertia is:
I = 3 (⅓ (135 kg) (3.75 m)²)
I = 1900 kg m²
(b) Net torque = moment of inertia × angular acceleration
∑τ = Iα
First, find the angular acceleration.
ω₀ = 0 rad/s
ω = 6.0 rev/s (2π rad/rev) = 37.7 rad/s
t = 8.0 s
α = (37.7 rad/s − 0 rad/s) / 8.0 rad/s = 4.71 rad/s²
∑τ = Iα
∑τ = (1900 kg m²) (4.71 rad/s²)
∑τ = 8950 kg m² / s²
∑τ = 8950 Nm