Answer:
a
Explanation:
The weight of your car will aslo affect its
Answer:
speed and acceleration
La distancia que existe entre las bases de un campo de béisbol es de 28 m. Si la pelota se batea por la línea en dirección a la tercera base con una velocidad de 32 m/s. ¿Con qué rapidez cambia la distancia entre la pelota y la primera base cuando se encuentra a la mitad del camino hacia la tercera base?
Answer: Could you put this in english plz
Explanation:
what is the impact of colloidal particles in water
Answer:
Colloids are very low diameter particles which are responsible for the turbidity or the color of surface water. Because of their very low sedimentation speed the best way to eliminate them is the coagulation-flocculation processes.
The recommended time weighted average air concentration for occupational exposure to water soluble hexavalent chromium (Cr VI) is 0.05 mg · m−3. This concentration is based on an assumption that the individual is generally healthy and is exposed for 8 hours per day, 5 days per week, 50 weeks per year, over a working lifetime (that is from age 18 to 65 years). Assuming a body weight of 78 kg and inhalation rate of 15.2 m3 · d−1 over the working life of the individual, what is the lifetime (75 years) CDI?
Answer: the lifetime (75 years) CDI is 0.001393 mg/kg.day
Explanation:
Given that;
CA = Contaminant Concentration = 0.05 mg/m³
IR = Inhalation Rate = 15.2m³per day = 15.2 / 24 = 0.6333 m³/hr
ET = Exposure Time = 8 hour per day
ED = Exposure Duration = (65 - 18 years) = 47
EF = Exposure Frequency = 5 day/week * 50 week/ year = 250 days/year
BW = Body Weight = 78 Kg
AT = Averaging Time = 75 years = (75 * 365 days) = 27375 days
Now to find the CDI (Chronic Daily Intake)' we say;
CDI = (CA×IR×ET×EF×ED) / ( BW×AT)
so we substitute;
CDI = (0.05 × 0.6333 × 8 ×250 × 47) / (78 × 27375)
CDI = 2976.51 / 2135250
CDI = 0.001393 mg/kg.day
therefore the lifetime (75 years) CDI is 0.001393 mg/kg.day
What kind of job does mike have? Mike’s job is to study blueprints, evaluate product stability, and to examine the safety of products. Mike’s works as a/n blank engineer with a manufacturing company.
Answer: a drafting engineer
Explanation:
Given int variables k and total that have already been declared, use a do...while loop to compute the sum of the squares of the first 50 counting numbers, and store this value in total. Thus your code should put 1*1 + 2*2 + 3*3 +... + 49*49 + 50*50 into total. Use no variables other than k and total.
Answer:
k-1000
Explanation:
Answer:
k = 1;
total = 0;
do {
total = total + (k*k);
k++;
} while (k <= 50);
Explanation:
answer using Java
A compressible fluid flows through a compressor that increases the density from 1 kg/m3 to 5 kg/m3. The cross-sectional area of the inlet pipe is 3 m2 and that of the discharge pipe is 1 m2. The relation between the discharge volume flow rate and the inlet volume flow rate is
Answer:
The relation between the discharge volume flow rate and the inlet volume flow rate is [tex]\frac{1}{5}[/tex].
Explanation:
No matter if fluid is compressible or not, mass throughout compressor, a device that works at steady state, must be conserved according to Principle of Mass Conservation:
[tex]\dot m_{in}-\dot m_{out} = 0[/tex] (Eq. 1)
Where [tex]\dot m_{in}[/tex] and [tex]\dot m_{out}[/tex] are mass flows at inlet and outlet, measured in kilograms per second.
After applying Dimensional analysis, we expand the equation above as follows:
[tex]\rho_{in}\cdot \dot V_{in} - \rho_{out}\cdot \dot V_{out} = 0[/tex] (Eq. 2)
Where:
[tex]\rho_{in}[/tex], [tex]\rho_{out}[/tex] - Fluid densities at inlet and outlet, measured in kilograms per cubic meter.
[tex]\dot V_{in}[/tex], [tex]\dot V_{out}[/tex] - Volume flow rates at inlet and outlet, measured in cubic meters per second.
After some algebraic handling, we find the following relationship:
[tex]\rho_{out}\cdot \dot V_{out} = \rho_{in}\cdot \dot V_{in}[/tex]
[tex]\frac{\dot V_{out}}{V_{in}} = \frac{\rho_{in}}{\rho_{out}}[/tex] (Eq. 3)
If we know that [tex]\rho_{in} = 1\,\frac{kg}{m^{3}}[/tex] and [tex]\rho_{out} = 5\,\frac{kg}{m^{3}}[/tex], then the relation between the discharge volume flow rate and the inlet volume flow rate is:
[tex]\frac{\dot V_{out}}{\dot V_{in}} = \frac{1\,\frac{kg}{m^{2}} }{5\,\frac{kg}{m^{3}} }[/tex]
[tex]\frac{\dot V_{out}}{\dot V_{in}} = \frac{1}{5}[/tex]
The relation between the discharge volume flow rate and the inlet volume flow rate is [tex]\frac{1}{5}[/tex].
Question #9
Multiple Choice
Which statement characterizes how the creation of LIMBS benefits developing countries?
O Using nanotechnology, a new material is created to benefit many other products
Using only natural materials, there is little chemical production, thus reducing the pollution in these countries
Using regional materials creates a sustainable program that breaks countries dependencies on other nations
Using fabricated materials, no natural resources are overfarmed, keeping the environment intact.
© 2014 Glynlyon, Inc.
Answer:
Using regional materials creates a sustainable program that breaks countries’ dependencies on other nations.
Explanation:
i did the assignment
Answer:
Using regional materials creates a sustainable program that breaks countries’ dependencies on other nations.
Explanation:
C
If a water heater operates at 20 amps on a 240 volt circuit, what is the wattage of the appliance?
Answer:
4800 watts
Explanation:
Power is the product of voltage and current:
P = VI = (240 V)(20 A) = 4800 W
The wattage is 4800 watts.
Will give correct answer brainliest!!
Fill in the blank.
_________ are engineers who help to develop products and projects by creating technical drawings
Answer:
Design engineer
Explanation:
A work cell is currently operated 2000 hr/yr by a human worker who is paid an hourly rate of $23.00, which includes applicable overhead costs. One work unit is produced in a cycle time of 4.8 min. Management would like to increase output to meet increasing demand and a robot cell is being considered as a replacement for the present manual cell. The cycle time of the proposed cell would be reduced to 4.0 min. The installed cost of the robot plus supporting equipment is $120,000. Power and other utilities to operate the robot will be $0.30/hr, and annual maintenance costs are $2500. Determine:
a. the number of parts produced annually by the manually operated cell.
b. cost per part produced.
c. how does the cost per part of the robot cell compare with your answer in part (b), given a 4-year service life, 10% rate of return, and no salvage value.
Answer:
a) 25000 pcs/yr
b) cost per part produced is $ 1.84 per pc
c) Cpc = $ 1.365 per pcs
Explanation:
a)
the relation to calculate the number of parts produced annually by manual process is;
Q = Hw / Tc
Hw is the hourly rate ( 2000hr/yr) and Tc is the cycle time ( 4.8 min)
so we substitute
Q = (2000 × 60) / 4.8
= 120000 / 4.8
= 25000 pcs/yr
b)
cost per part produced
the relation to calculate the cost per part produced is expressed as;
Cpc = $23(Hw) / Q
Cpc is the cost per part produced
so we substitute
Cpc = $23(2000) / 25000
= 46000 / 25000
= $ 1.8 per pc
therefore cost per part produced is $ 1.84 per pc
c)
for the robot cell, at a service life of 4 years and a 10% rate of return , the factor is expressed as;
f = [r(1 + r)^t] / [((1 + r)^t ) - 1 ]
our rate r = 10% = 0.1 and our t = 4
so we substitute
f = [0.1 (1 + 0.1)^4] / [((1 + 0.1)^4 ) - 1 ]
f = 0.14641 / 0.4641
f = 0.3155
now we find the total cost
TC = 120000(0.3155) + 2000(0.3) + 2500
TC = $ 40,960
next we find the parts produced annually
Q = (2000 × 60) / 4
Q = 120,000 / 4
Q = 30000 pcs/yr
finally we find the cost per part produced;
Cpc = TC / Q
we substitute
Cpc = 40,960 / 30000
Cpc = $ 1.365 per pcs
which is one of the most important steps to do before you go into an interview ?
Research the company
Tell your current boss
Buy a new dressy outfit
Finish school
Answer:
Research the company
Explanation:
It is a good idea to find out information about the company you are interviewing. Among other things, this will help you decide if you actually want to work for that company.
Telling your current boss can be risky to your job. A new outfit may be helpful for certain positions--especially those where manner of dress is important. Finishing school may or may not be an important requirement for the position you're seeking. Your company research will tell you.
Researching the company is one of the most important steps to take.
Complete the sentence using the correct term.
are made without yeast and are often savory or sweet.
Answer:
Quick Breads
Explanation:
I think this is correct. I am not for sure i just looked it up and it says word for word that this is the answer.
Answer:
Quick Breads
Explanation:
I got it right on my Plato test
Which phase involves research to determine exactly what the client expects?
brainstorming
identifying the need
preventive maintenance
building a model
The phase identifying the need involves research to determine exactly what the client expects. The correct option is B.
What is research?
Research is a systematic inquiry process that includes data gathering, documentation of important information, analysis, and interpretation of that data and information.
These all are in accordance with appropriate procedures established by particular academic and professional disciplines.
Action-informing research is its goal. As a result, your study should attempt to place its findings in the perspective of the wider body of knowledge. In order to develop knowledge that is usable outside of the research setting, research must constantly be of the highest calibre.
Research is done during the step of determining the need to ascertain the precise expectations of the client.
Thus, the correct option is B.
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The site earthwork in Phase III of Four Hills Landfill project included a 3.0 ft deep cut across an entire 2.5-acre site. Soil was excavated from within the proposed Phase III footprint. The average unit weight of this soil is 118 lb/ft3, and the average moisture content is 9.6%. It also has a maximum dry unit weight of 122 lb/ft3 and an optimum moisture content of 11.1%, based on the modified Proctor test. The excavated soil will be placed on a nearby site and compacted to an average relative compaction of 93%. Compute the volume of fill that will be produced and express your answer in cubic yards.
Answer: 11470.4 cubic yards
Explanation:
first we calculate the volume of the site;
V1 = Area × depth
V1 = 2.5 acre × (43560 ft² / 1 acre )×3ft
V1 = 326700 ft
next we is the relative compaction
RC = [γd(field) / γdmax(laboratory)] × 100
so we substitute
93 = [γd(field) / 122 lb/ft³)] × 100
γd(field) = 113.46 lb/ft³
then the dry unit weight of the site
γday1 = γavg / ( 1 + w)
= 118 lb/ft³ / ( 1 + (9.6/100))
= 118 lb/ft³ /1.096
= 107.664 lb/ft³
finally we find the fill volume of the site
V2/V1 = γd / γd(field)
we substitute
V2/326700 = 107.664 / 113.46
V2 = 310010.83 ft³
we convert to cubic yards
= 310010.83 ft³ × (0.037 cubic yard / 1 ft³)
= 11470.4 cubic yards
One method that is used to grow nanowires (nanotubes with solid cores) is to initially deposit a small droplet of a liquid catalyst onto a flat surface. The surface and catalyst are heated and simultaneously exposed to a higher-temperature, low-pressure gas that contains a mixture of chemical species from which the nanowire is to be formed. The catalytic liquid slowly absorbs the species from the gas through its top surface and converts these to a solid material that is deposited onto the underlying liquid-solid interface, resulting in construction of the nanowire. The liquid catalyst remains suspended at the tip of the nanowire. Consider the growth of a 15-nm-diameter silicon carbide nanowire onto a silicon carbide sururface. The surface is maintained at a temperature of Ts = 2400 K and the particular liquid catalyst that is used must be maintained in the range 2400 K ≤ Tc ≤ 3000 K to perform its function. Determine the maximum length of a nanowire that may be grown for conditions characterized by h = 105 W/m2.K and T[infinity] = 8000 KT. Assume properties of the nanowire are the same as for bulk silicon carbide.
Answer: maximum length of the nanowire is 510 nm
Explanation:
From the table of 'Thermo physical properties of selected nonmetallic solids at At T = 1500 K
Thermal conductivity of silicon carbide k = 30 W/m.K
Diameter of silicon carbide nanowire, D = 15 x 10⁻⁹ m
lets consider the equation for the value of m
m = ( (hP/kAc)^1/2 ) = ( (4h/kD)^1/2 )
m = ( ((4 × 10⁵)/(30×15×10⁻⁹ ))^1/2 ) = 942809.04
now lets find the value of h/mk
h/mk = 10⁵ / ( 942809.04 × 30) = 0.00353
lets consider the value θ/θb by using the equation
θ/θb = (T - T∞) / (T - T∞)
θ/θb = (3000 - 8000) / (2400 - 8000)
= 0.893
the temperature distribution at steady-state is expressed as;
θ/θb = [ cosh m(L - x) + ( h/mk) sinh m (L - x)] / [cosh mL+ (h/mk) sinh mL]
θ/θb = [ cosh m(L - L) + ( h/mk) sinh m (L - L)] / [cosh mL+ (h/mk) sinh mL]
θ/θb = [ 1 ] / [cosh mL+ (h/mk) sinh mL]
so we substitute
0.893 = [ 1 ] / [cosh (942809.04 × L) + (0.00353) sinh (942809.04 × L)]
L = 510 × 10⁻⁹m
L = 510 nm
therefore maximum length of the nanowire is 510 nm
NEEDS TO BE IN PYTHON:ISBN-13 is a new standard for indentifying books. It uses 13 digits d1d2d3d4d5d6d7d8d910d11d12d13 . The last digit d13 is a checksum, which is calculated from the other digits using the following formula:10 - (d1 + 3*d2 + d3 + 3*d4 + d5 + 3*d6 + d7 + 3*d8 + d9 + 3*d10 + d11 + 3*d12) % 10If the checksum is 10, replace it with 0. Your program should read the input as a string. Display "incorrect input" if the input is incorrect.Sample Run 1Enter the first 12 digits of an ISBN-13 as a string: 978013213080The ISBN-13 number is 9780132130806Sample Run 2Enter the first 12 digits of an ISBN-13 as a string: 978013213079The ISBN-13 number is 9780132130790
Answer:
Follows are the code to this question:
n=input("Enter the first 12 digits of an ISBN-13 as a string:")#defining a varaible isbn for input value
if len(n)!=12: #use if block to check input value is equal to 12 digits
print("incorrect input") #print error message
elif n.isdigit()==False: #use else if that check input is equal to digit
print("incorrect input") #print error message
else:# defining else block
s=0 #defining integer vaiable s to 0
for i in range(12):#defining for loop to calculate sum of digit
if i%2==0: #defining if block to check even value
s=s+int(n[i])#add even numbers in s vaiable
else: #use else block for odd numbers
s=s+int(n[i])*3 #multiply the digit with 3 and add into s vaiable
s=s%10#calculate the remainder value
s=10-s#subtract the remainder value with 10 and hold its value
if s==10: #use if to check s variable value equal to 10
s=0#use s variable to assign the value 0
n=n+s.__str__() #u
Output:
please find attached file.
Explanation:In the above Python code, the "n" variable is used for input the number into the string format uses multiple conditional statements for a check input value, which can be defined as follows:
In if block, it checks the length isn't equal to 12, if the condition true, it will print an error message. In the else, if the block it checks input value does not digit, if the condition is true, it will print an error message. In the else block, it uses the for loop, in which it calculates the even and odd number sum, and in the odd number, we multiply by 3 then add into s variable. In this, the s variable is used to calculate its remainder and subtract from the value and use the if block to check, its value is not equal to 10 if it's true, it adds 0 into the last of n variable, otherwise, it adds its calculated value.A DC servomotor has a torque constant of 0.075 N-m/A and a voltage constant of 0.12 V/(rad/sec). The armature resistance is 2.5 Ohm. A terminal voltage of 24 V is used to operate the motor. Determine:
a) the starting torque generated by the motor just as the voltage is applied.
b) the maximum speed at a torque of zero.
c) the operating point of the motor when it is connected to a load whose torque characteristic is proportional to speed with a constant of proportionality = 0.0125 N-m/(rad/sec).
Answer:
The answer is below
Explanation:
Given that:
[tex]k_t=torque\ constant=0.075\ Nm/A\\\\k_v=voltage\ constant=0.12\ V/(rad/sec)\\\\R_a=armature \ resistance=2.5 \Omega\\\\V_t=terminal\ voltage=24\ V\\\\a)The \ starting\ current\ I_a\ is\ given \ as:\\\\I_a=\frac{V_t}{R_a} =\frac{24}{2.5} =9.6\ A\\\\The \ starting\ torque(T)\ is:\\\\T=k_tI_a=0.075*9.6=0.72\ N.m[/tex]
b) The maximum speed occurs when the terminal voltage and back emf are equal to each other i.e.
[tex]V_t=e_b=k_v\omega\\\\\omega=\frac{V_t}{k_v}=\frac{24}{0.12} =200\ rad/s[/tex]
c) The load torque is given as:
[tex]T_L=0.0125\Omega\\\\The\ motor\ torque \ is:\\\\T=k_t(\frac{V_t-k_v\omega}{R_a} )\\\\but\ T = T_L,hence:\\\\0.0125\omega=0.075(\frac{24-0.12\omega}{2.5} )\\\\0.03125\omega=1.8-0.009\omega\\\\0.04025\omega=1.8\\\\\omega=44.72\ rad/sec\\\\N=\frac{60\omega}{2\pi} =\frac{60*44.72}{2\pi} =427\ rpm[/tex]
Chad is working on a design that uses the pressure of steam to control a valve in order to increase water pressure in showers. Which statement describes what his design is dealing with? viscosity, the resistance to flow that fluids exhibit elasticity, the indicator of how easily a fluid will return to its original volume after a force is removed from the fluid compressibility, the property that describes the amount of volume that decreases when pressure is applied to a fluid hydraulics, the use and study of liquid fluids and their motions, behaviors, and interactions
Answer:
C: Viscosity, the resistance to flow that fluids exhibit
Explanation:
Did it on Edge :)
Answer:
C: Viscosity, the resistance to flow that fluids exhibit
Explanation:
4. Which of these is typically NOT a function of the flywheel?
OA. Power transfer to the transmission
OB. Engage the Starter
OC. Smooth out power pulses
OD. Balance the crankshaft
Answer:D
Explanation:
Option D is correct. Balancing the crankshaft is NOT one of the functions of a flywheel.
A flywheel is part of an automobile. It is a heavy wheel that is attached to a rotating shaft of an automobile. Since there may be the presence of large forces within an automobile structure, the presence of a flywheel helps to balance the force evenly across it.
Some of the functions of the flywheel are but are not limited to help in transferring power to the transmission, engaging the starter, and smoothing out of power pulses.
Hence based on the explanation above, balancing the crankshaft is NOT one of the function of a flywheel.
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Pls help I will mark brainlesst
Answer:
Ribosomes 1
Explanation
Ribosomes are small structures where proteins are made. Although they are not enclosed within a membrane, they are frequently considered organelles. Each ribosome is formed of two subunits, like the one pictured at the top of this section. Both subunits consist of proteins and RNA
which one of these reduce fraction?
The structure consists of a very large steel plate they will be used to transfer an in plane tensile stress. You have information from the company that performed a non-destructive testing technique if there are any flaws inside the plate. This non-destructive testing technique is based on ultrasonic wave transmission and will only detect a crack if it is bigger than 2.5 mm. No flaws were detected in the plate. You decided to pull some samples from a similar plate and you determined that the KIC value of these plates are 40 MPa*m0.5.
Required:
Estimate the maximum in plane tensile stress that you would suggest that this plate should carry.
Answer:
[tex]\mathbf{\sigma_{max} =638.308 \ MPa}[/tex]
Explanation:
For any large steel plate with an infinite length and width and a center through the crack under tension, the stress intensity factor can be expressed as:
[tex]K_I = \sigma \sqrt{\pi a}[/tex]
where;
a = 2.5 mm/2
a = 1.25 mm
a = 1.25 × 10⁻³ m
Therefore; the maximum stress in tension capacity can be computed as;
[tex]\sigma_{max} = \dfrac{K_{I_C}}{\sqrt{\pi a_c}}[/tex]
[tex]\sigma_{max} = \dfrac{40}{\sqrt{\pi \times 1.25 \times 10^{-3}}}[/tex]
[tex]\mathbf{\sigma_{max} =638.308 \ MPa}[/tex]
Which courses might a mechanical engineer take in college
Answer:
Fluid dynamics.
Materials science.
Robotics.
Manufacturing processes.
Thermodynamics and heat transfer.
Environmental science.
Explanation:
What must be done before you change the polarity on a welding machine?
ur answer
Answer:
Usually it can be changed by flipping a switch. If your machine does not have one, then you just need to exchange the cables to the electrode holder and ground clamp.
Explanation:
The things that must be done before you change the polarity on a welding machine are coarse and fine adjustment.
What is a welding machine?The heated tool assembly, with two exposed surfaces, and two fixtures for holding the component parts to be welded. The tooling is for bringing the component parts into contact with the heated tool and bringing the molten joint surfaces together to form the weld. And displacement stops on the platen and holding fixtures make up a heated tool welding machine.
Polarity refers to the fact that the electrical circuit formed when you turn on the welder contains a negative and a positive pole. When welding, polarity is crucial, since the weld's strength and quality are affected by the choice of polarity.
Therefore, before changing the polarity of welding equipment, coarse and fine adjustments must be made.
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State whether the following statements are true or false. Provide a brief justification for your answer.
a. Consider a SDOF system with Coulomb damping. When displaced from the equilibrium position and released, the mass may not move at all.
b. Consider a SDOF system with an ideal viscous damper. When displaced from the equilibrium position and released, the mass will always undergo oscillatory motion.
c. The damped natural frequency of a system is always greater than the undamped natural frequency
d. For an undamped system undergoing a harmonic forcing, the amplitude of the response approaches zero as the forcing frequency becomes very high.
e. The amplitude of free response of SDOF system with Coulomb damping decreases
Answer:
[a] False.
[b]. True
[c]. false.
[d]. true.
[e]. true.
Explanation:
NB: SDOF simply means Simple Degree Of Freedom, that is to say it is a system that can be solved by differential equation such as the second order and the single differential equation.
So, the question asked us to determine if each of the scenario is true or false.
a. Consider a SDOF system with Coulomb damping. When displaced from the equilibrium position and released, the mass may not move at all.
ANSWER: FALSE.
REASON: The mass moved a little bit When displaced from the equilibrium position and released.
b. Consider a SDOF system with an ideal viscous damper. When displaced from the equilibrium position and released, the mass will always undergo oscillatory motion.
ANSWER: TRUE
REASON: for an ideal viscous damper. When displaced from the equilibrium position and released, the mass will always undergo oscillatory motion.
c. The damped natural frequency of a system is always greater than the undamped natural frequency
.
ANSWER: FALSE
REASON: The damped natural frequency of a system is always greater than the undamped natural frequency
d. For an undamped system undergoing a harmonic forcing, the amplitude of the response approaches zero as the forcing frequency becomes very high.
ANSWER: TRUE
REASON: the amplitude of the response approaches zero as the forcing frequency becomes very high for undamped system undergoing a harmonic forcing
e. The amplitude of free response of SDOF system with Coulomb damping decreases
ANSWER: TRUE
REASON: amplitude of free response of SDOF system with Coulomb damping decreases
Select all the correct answers. What are two reasons why the terrestrial planets formed closer to the sun after a supernova event that initiated the formation of the solar system?
What are the 3 common ladder materials?
Answer:
Aluminium, Timber, Fibreglass
Explanation:
Most ladders are made of aluminium to have resistance against oxidisation and avoid rust; aluminium also doesnt spark either and is non magnetic. Some ladders are made out of timber like Douglas Fir, Oak, and Hickory. Some ladders are made out of fibreglass because it is strong and sturdy. They are also very to carry and are electrically resistant and heat tolerant.
T.J. wants to send a friend a file with a funny dancing cat. Which file format should T.J. use?
DOCX
GIF
MP3
PDF
Answer:
T. J. should the file by GIF to his friend.
beeeeeeeeeeeeeeeeeeeeeeeeep its gif
Assignment 1: Structural Design of Rectangular Reinforced Concrete Beams for Bending
Perform structural design of a rectangular reinforced concrete beam for bending. The beam is simply supported and has a span L=20 feet. In addition to its own weight the beam should support a superimposed dead load of 0.50 k/ft and a live load of 0.65 k/ft. Use a beam width of 12 inches. The depth of the beam should satisfy the ACI stipulations for minimum depth and be proportioned for economy. Concrete compressive strength f’c = 4,000 psi and yield stress of reinforcing bars fy = 60,000 psi. Size of stirrups should be chosen based on the size of the reinforcing bars. The beam is neither exposed to weather nor in contact with the ground, meaning it is subjected to interior exposure.
• Use the reference on "Practical Considerations for Rectangular Reinforced Concrete Beams"
• Include references to ACI code – see slides from second class
• Include references to Tables from Appendix A
• Draw a sketch of the reinforced concrete beam showing all dimensions, number and size of rebars, including stirrups.
Answer:
Beam of 25" depth and 12" width is sufficient.
I've attached a detailed section of the beam.
Explanation:
We are given;
Beam Span; L = 20 ft
Dead load; DL = 0.50 k/ft
Live load; LL = 0.65 k/ft.
Beam width; b = 12 inches
From ACI code, ultimate load is given as;
W_u = 1.2DL + 1.6LL
Thus;
W_u = 1.2(0.5) + 1.6(0.65)
W_u = 1.64 k/ft
Now, ultimate moment is given by the formula;
M_u = (W_u × L²)/8
M_u = (1.64 × 20²)/8
M_u = 82 k-ft
Since span is 20 ft, it's a bit larger than the average span beams, thus, let's try a depth of d = 25 inches.
Effective depth of a beam is given by the formula;
d_eff = d - clear cover - stirrup diameter - ½Main bar diameter
Now, let's adopt the following;
Clear cover = 1.5"
Stirrup diameter = 0.5"
Main bar diameter = 1"
Thus;
d_eff = 25" - 1.5" - 0.5" - ½(1")
d_eff = 22.5"
Now, let's find steel ratio(ρ) ;
ρ = Total A_s/(b × d_eff)
Now, A_s = ½ × area of main diameter bar
Thus, A_s = ½ × π × 1² = 0.785 in²
Let's use Nominal number of 3 bars as our main diameter bars.
Thus, total A_s = 3 × 0.785
Total A_s = 2.355 in²
Hence;
ρ = 2.355/(22.5 × 12)
ρ = 0.008722
Design moment Capacity is given;
M_n = Φ * ρ * Fy * b * d²[1 – (0.59ρfy/fc’)]/12
Φ is 0.9
f’c = 4,000 psi = 4 kpsi
fy = 60,000 psi = 60 kpsi
M_n = 0.9 × 0.008722 × 60 × 12 × 22.5²[1 - (0.59 × 0.008722 × 60/4)]/12
M_n = 220.03 k-ft
Thus: M_n > M_u
Thus, the beam of 25" depth and 12" width is sufficient.