True. Air entrainment is an admixture that is added to concrete mixes to increase the durability and workability of the concrete. It helps reduce the potential for cracking and damage due to freeze-thaw cycles.
It can also improve the overall strength and stability of the concrete. By introducing small air bubbles into the mix, air entrainment can help decrease the shrinkage of the concrete and make it more resistant to damage over time. Overall, air entrainment is a useful tool for creating high-quality, long-lasting concrete structures.
Water expands by around 9% whenever it freezes. Pressure is created in the freeze-thaw cycles concrete's pores as a result of the water in moist concrete freezing. The expansion, cracking, scaling, and crumbling of damp concrete can eventually be brought on by freeze-thaw cycles, aggregate disruption, and other factors.
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: A spring is made from 0.1055-in-diameter wire. If the spring has a free length of 3 in., a spr. constant of 20 1b/in., and 10 total coils (ground and squared ends), the force (lb) required to fu compress the spring is most nearly: (A) 14 (B) 32 (C) 39 (D) 71
The force (lb) required to fu compress the spring is most nearly 71.
To find the force required to fully compress the spring, we can use the formula for the spring force:
F = kx
where F is the force applied, k is the spring constant, and x is the displacement from the free length.
First, let's find the mean diameter of the spring:
d = 0.1055 in.
The mean diameter is the average of the wire diameter and the diameter of the coil, so:
mean diameter = d + 10/3 * d = 1.485 in.
Next, let's find the spring constant:
k = 20 lb/in.
Finally, let's find the displacement from the free length when the spring is fully compressed:
total length of spring = 3 in. + 10 coils * mean diameter = 18.85 in.
fully compressed length of spring = total length of spring - 10 coils * wire diameter = 15.39 in.
displacement from free length = 3 in. - 15.39 in. = -12.39 in.
Note that the negative sign indicates that the displacement is in the opposite direction of the spring's natural length.
Now we can use the formula for spring force to find the force required to fully compress the spring:
F = kx = 20 lb/in. * (-12.39 in.) = -247.8 lb.
The negative sign indicates that the force is in the opposite direction of the applied force, so the actual force required to compress the spring is:
F = |-247.8 lb.| = 247.8 lb.
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what is the approximate resistance of a 40 lightbulb if the ac voltage provided to it is given by ? u(t) = 200%/2 cos(100mt)? R= (within three significant digits) Try question again Correct answer R-400 Ω
The approximate resistance of a 40-lightbulb can be calculated using the formula V = IR, where V is the voltage, I is the current, and R is the resistance.
In this case, the voltage provided to the bulb is given by u(t) = 200%/2 cos(100mt). To simplify this expression, we can first convert 200% to 2, since 200% equals twice the original value. Then, we can divide 2 by 2 to get 1 and multiply it by the maximum voltage of the waveform, which is 2. This gives us a maximum voltage of 2V.
Next, we need to find the current flowing through the bulb. To do this, we can use Ohm's law, which states that I = V/R, where I is the current, V is the voltage, and R is the resistance. In this case, we can rearrange the formula to get R = V/I, and substitute the values we have:
R = 2V / I
To find the current, we need to know the expression for the current waveform. Since the waveform is not given in the question, we can assume that the bulb is an ideal resistor, which means that the current waveform will be the same as the voltage waveform, but with a different amplitude. Specifically, the amplitude of the current waveform will be V/R, since V = IR.
Therefore, the current waveform can be expressed as i(t) = 2/R cos(100mt), and the waveform's amplitude is 2/R. We can substitute this expression into the formula for R, and solve for R:
R = 2V / i_max = 2V / (2/R) = R^2V / 2
Solving for R, we get:
R = sqrt(2V / i_max) = sqrt(2*2V / 2) = sqrt(2V) = sqrt(2*2) = 2
Therefore, the approximate resistance of the 40 lightbulbs is R = 400 Ω (within three significant digits).
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here in Denver the atmospheric pressure is usually around 12.1 psi. The pump manufacturers specification is 5 in. He. Since one inch of mercury is approximately a half psi, we have plenty of pressure to work with. (clarify this erroneous statement).-S 7o 23 exercise operation at the suction side of a pump 50 points INSTRUCTIONS: Cormment on the following statements 1. STATEMENT We cavitated four purnmps to death before we found the crack in the suction line. (Explain the difference between cavitation and the situation described by the statement) Carv, tahin. s the fo wahn and collapse of gaseous cavities 2 STATEMENT Here in Denver, the atmospheric prossure is usually around 12.1 psla (0.8 bar). The pump manufacturers specfication is 5 in.Hg. (0.17 ban, Since one inch of morcury is approximately a half psi, wo have plenty of pressurs to work with. (Clarify this erroneous statement) You usill b 1 in H over pump manulactun specs. , STATEMENT I dont understand whats wrong with my pump, It makes a high shrieking sound. And, I dont get the flow hat is stated in the manufacturers catalog. I thought the pump might not be dovoloping onough vacuum, so I chocked the vacuum with a gage. The gage reads 24 (0,01 bar) and the pump catalog says I only need 6 0 204 bar), (Whats happening to the pump? Clarily the last sontonce in the statoment) indicaton cavita onSultaneus collaspe o 4, STATEMENT purchasing bought a different brand of pump and it cavitated right off tho bat. We cant determine why. since the flow rate tirough the suction line is exadily the samo, Whats the problom?) cor suedl in desig n or ncovrect sud viscesily 6 STATEMET ByrSS our hachines were leaking like crazy so we switched to a heavier oil. Now the pump is nolsy and doosnt last 1o0 oo long ither (Whats happening to the pump and what caused the eiluation?)
Cavitation is the formation and collapse of gaseous cavities, while the situation described in the statement is a crack in the suction line.
1. Cavitation occurs when there is low pressure at the suction side of the pump, causing the formation of bubbles that collapse when they reach the high-pressure area, causing damage to the pump.
2. The statement is incorrect because the pressure unit of inches of mercury (in. Hg) cannot be directly converted to pressure units of psi or bar. However, if the pump manufacturer's specification is in inches of mercury, it can be converted to pressure units using a conversion table. If the atmospheric pressure is higher than the manufacturer's specification, it may be necessary to reduce the pressure at the suction side of the pump to avoid damage from cavitation.
3. The high shrieking sound and lower flow rate indicated by the gauge could be due to cavitation, as indicated by the last sentence of the statement. The pump may not be able to handle the required flow rate due to the low pressure at the suction side caused by cavitation. The pressure at the suction side may need to be increased or the pump may need to be replaced with one that can handle the required flow rate.
4. The problem with the pump could be due to design issues or incorrect suction line sizing, which can cause cavitation. The flow rate through the suction line may be the same, but if the pump is not designed to handle the specific conditions of the system, it can lead to cavitation and damage to the pump.
5. The heavier oil may be causing the pump to make noise and not last as long because it may be too thick for the pump and not providing adequate lubrication. The heavier oil may also be causing increased resistance, which can lead to overheating and damage to the pump. A lighter oil or one that is recommended by the pump manufacturer should be used instead.
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T/F suppose instr1 is fetched in stage 1. instr1 then proceeds to stage 2, reg read. in a pipelined implementation, can instruction2 be fetched simultaneously with that reg read.
True, in a pipelined implementation, instruction2 can be fetched simultaneously with the register read of instruction1. This is because pipelining allows multiple instructions to be executed at different stages concurrently, thus improving the overall performance and throughput of the processor.
True, in a pipelined implementation, instruction2 can be fetched simultaneously with the reg read of instruction1. This is because pipelining allows for multiple instructions to be executed concurrently by breaking down the instruction processing into multiple stages. Each stage can handle a different instruction, allowing for overlapping of instruction processing and thus increasing overall performance.
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