Answer:
The term Accuracy means that how close our result to the original result.
Suppose we do any experiment in laboratory and we calculate mass = 7 kg but answer is mass = 15 kg then our answer is not accurate.
And the term Precision means how likely we get result like this.
Suppose we do any experiment in laboratory and we calculate mass five times and each time we get mass = 7 kg then our answer is precised but not accurate.
Four kilograms of gas were heated at a constant pressure of 12 MPa. The gas volumes were 0.005 m^3 and 0.006 m^3 in the initial and final states, respectively, and 3.9 kJ of heat was transferred to the gas. What is the change in specific internal energy between the initial and final states?
Answer:
Specific change in internal energy is - 2.025 kj/kg.
Explanation:
The process is constant pressure expansion. Apply first law of thermodynamic to calculate the change in internal energy.
Given:
Mass of gas is 4 kg.
Initial volume is 0.005 m³.
Final volume is 0.006 m³.
Pressure is 12 Mpa.
Heat is transfer to the gas. So it must be positive 3.9 kj.
Calculation:
Step1
Work of expansion is calculated as follows:
[tex]W=P(V_{f}-V_{i})[/tex]
[tex]W=12\times10^{6}(0.006-0.005)[/tex]
W=12000 j.
Or,
W=12 Kj.
Step2
Apply first Law of thermodynamic as follows:
Q=W+dU
3.9=12+dU
dU = - 8.1 kj.
Step3
Specific change in internal energy is calculated as follows:
[tex]u=\frac{U}{m}[/tex]
[tex]u=\frac{-8.1}{4}[/tex]
u= - 2.025 kj/kg.
Thus, the specific change in internal energy is - 2.025 kj/kg.
Can someone work this problem out completly?
A 3 kg model rocket is launched vertically and reaches
andaltitude of 60 m wih a speed of 28 m/s at the end of flight,
timet=0. As the rocket approaches its maximum altitude itexplodes
into two parts of masses Ma = 1 kg and Mb = 2 kg. Part A is
observed to strike the ground 74.4 m west of the launchpoint at t =
5.85 s. Determine the position of part B at thattime.
Answer:
Part B will be 37.2 m to the east of the launch point at an altitude of 80.8 m
Explanation:
At t0 the rocket is at 60 m and has a speed of 28 m/s.
Then it explodes when it reaches max altitude.
Since the rocket will have its engine off after t0 it will be in free fall.
It will be affected only by the acceleration of gravity, so it moves with constant acceleration, we can use this equation.
Y(t) = Y0 + V0*t + 1/2*a*t^2
Y0 = 60 m
V0 - 28 m/s
a = g = -9.81
We also have the equation for speed:
V(t) = V0 + a*t
And we know that when it reaches its highest point it ill have a speed of zero.
0 = V0 + a * t
a * t = -V0
t = -V0 / a
t = -28 / -9.81 = 2.85 s
This is the time after t0 when the engine ran of of fuel.
Using this value on the position equation:
Y(2.85) = 60 + 28*2.85 + 1/2*(-9.81)*2.85^2 = 100 m
At an altitude of 100 m it explodes in two parts. An explosion is like a plastic collision in reverse, momentum is conserved.
Since the speed of the rocket is zero at that point, the total momentum will be zero too.
Part A, with a mass of 1 kg fell 74.4 m west of the launch point. It fell in a free fall with a certain initial speed given to it by the explosion. This initial speed had vertical and horizontal components.
First the horizontal. In the horizontal there is no acceleration (ignoring aerodynamic drag).
X(t) = X1 + Vx1 * (t - t1)
X1 = 0 because it was right aboce the launch point. t1 is the moment of the explosion.
t1 = 2.85 s
We know it fell to the ground at t = 5.85 s
Vx1 * (t2 - t1) = X(t2) - X1
Vx1 = (X(t2) - X1) / (t2 - t1)
Vx1 = (74.4 - 0) / (5.85 - 2.85) = 24.8 m/s
Now the vertical speed
Y(t2) = Y1 + Vy1*(t2 - t1) + 1/2*a*(t2 - t1)^2
Vy1*(t2 - t1) = Y(t2) - 1/2*a*(t2 - t1)^2 - Y1
Y(t2) = 0 because it is on the ground.
Vy1 = (-1/2*a*(t2 - t1)^2 - Y1) / (t2 - t1)
Vy1 = (-1/2*-9.81*(5.85 - 2.85)^2 - 100) / (5.85 - 2.85) = -18.6 m/s
If the part A had a speed of (24.8*i - 18.6*j) m/s, we calcultate the speed of part 2
Horizontal:
vxA * mA + vxB * mB = 0
-vxA * mA = vxB * mB
vxB = -vxA * mA / mB
vxB = -24.8 * 1 / 2 = -12.4 m/s
Vertical:
vyA * mA + vyB * mB = 0
-vyA * mA = vyB * mB
vyB = -vyA * mA / mB
vyB = -(-16.6) * 1 / 2 = 8.3 m/s
Now that we know its speed and position at t1 we can know ehre it will be at t2
X(t) = 0 - 12.4 * (t - t1)
X(5.85) = -12.4 * (5.85 - 2.85) = -37.2 m
Y(t) = 100 + 8.3 * (t - t1) + 1/2 * (-9.8) * (t - t1)^2
Y(t) = 100 + 8.3 * (5.85 - 2.85) + 4.9 * (5.85 - 2.85)^2 = 80.8 m
Part B will be 37.2 m to the east of the launch point at an altitude of 80.8 m
A(n)_____is an interconnected collection of computers.
Answer:
Network is a collection of computers
Explanation:
A network is a gathering of at least two gadgets that can convey. Practically speaking, a system is included various distinctive PC frameworks associated by physical or potentially remote associations.
The scale can run from a solitary PC sharing out fundamental peripherals to huge server farms situated far and wide, to the Internet itself. Despite extension, all systems permit PCs or potentially people to share data and assets.
Determine the mass of a car that weight 3,500 lbs both in slugs and kilograms. The answer should be in kilograms.
Answer:
The mass of car in slug =108.5 slug.
The mass of car in kilogram =1575 Kg.
Explanation:
Given that
Mass of car = 3500 lbs
We know that
1 lbs =0.031 slug
So
3500 lbs = 0.031 x 3500 slug
So the mass of car in slug =108.5 slug.
We know that
1 lbs =0.45 kilograms
so
3500 lbs = 3500 x 0.45 Kg
So the mass of car in kilogram =1575 Kg.
A water jet that leaves a nozzle at 60 m/s at a certain flow rate generating power of 250 kW by striking the buckets located on the perimeter of a wheel. Determine the mass flow rate of the jet.
Answer:
The mass flow rate of jet =69.44 kg/s
Explanation:
Given that
velocity of jet v= 60 m/s
Power P=250 KW
As we know that force offered by water F
[tex]F=\rho\ A \ v^2[/tex]
Power P= F.v
So now power given as
[tex]P=\rho\ A \ v^3[/tex]
We know that mass flow rate = ρAv
[tex]P=mass\ flow\ rate\ \times v^2[/tex]
250 x 1000 = mass flow rate x 3600
mass flow rate = 69.44 kg/s
So the mass flow rate of jet =69.44 kg/s
What is 1000 kJ/sec in watts?
Answer:
1000000 watts
Explanation:
1 kJ/sec= 1000 watts (or 1 watt= 0.001 kJ/sec)
Therefore,
1000 kJ/sec = 1000 x 1000 watts
= 1000000 watts
A kJ/sec (Kilojoule per second) is a unit used to measure power. It comes from the SI (Standard International) unit J/sec (Joule per second).
1 J/sec= 1 watt
Power is the energy transferred by a force per unit of time.
Energy is measured in Joules.
In this question, we are working out how much energy is transferred in watts.
You are hitting a nail with a hammer (mass of hammer =1.8lb) the initial velocity of the hammer is 50 mph (73.33 ft/sec). The time of impact is .023 sec. Assuming the nail heads directly in the -j direction, what is the magnitude of the force exerted on the hammer from the nail?
Answer:
The nail exerts a force of 573.88 Pounds on the Hammer in positive j direction.
Explanation:
Since we know that the force is the rate at which the momentum of an object changes.
Mathematically [tex]\overrightarrow{F}=\frac{\Delta \overrightarrow{p}}{\Delta t}[/tex]
The momentum of any body is defines as [tex]\overrightarrow{p}=mass\times \overrightarrow{v}[/tex]
In the above problem we see that the moumentum of the hammer is reduced to zero in 0.023 seconds thus the force on the hammer is calculated using the above relations as
[tex]\overrightarrow{F}=\frac{m(\overrightarrow{v_{f}}-\overrightarrow{v_{i}})}{\Delta t}[/tex]
[tex]\overrightarrow{F}=\frac{m(0-(-73.33)}{0.23}=\frac{1.8\times 73.33}{0.23}=573.88Pounds[/tex]
A tensile force of 9 kN is applied to the ends of a solid bar of 7.0 mm diameter. Under load, the diameter reduces to 5.00 mm. Assuming uniform deformation and volume constancy, (a) determine the engineering stress and strain; (b) determine the true stress and strain.
Answer:
Explanation:
Given
Force=9 kN
Diameter reduces from 7 mm to 5 mm
As volume remains constant therefore
[tex]A_0L_0=A_fL_f[/tex]
[tex]7^2\times L_0=5^2\times L_f[/tex]
[tex]\frac{L_0}{L_f}=\frac{25}{49}[/tex]
Thus Engineering Strain [tex]\epsilon _E=\frac{L_f-L_0}{L_0}[/tex]
[tex]=\frac{49}{25}-1=\frac{49-25}{25}=0.96[/tex]
Engineering stress[tex]=\frac{Load}{original\ Cross-section}[/tex]
[tex]\sigma _E=\frac{9\times 10^3}{\frac{\pi 7^2}{4}}=233.83 MPa[/tex]
(b)True stress
[tex]\sigma _T=\sigma _E\left ( 1+\epsilon _E\right )[/tex]
[tex]\sigma _T=233.83\times (1+0.96)=458.30 MPa[/tex]
True strain
[tex]\epsilon _T=ln\left ( 1+\epsilon _E\right )[/tex]
[tex]\epsilon _T=ln\left ( 1.96\right )=0.672[/tex]
Water at room temperature of 20.0°C is poured into an aluminum cylinder which has graduation markings etched on the inside. The reading in the graduations is 300.0 cc. The cylinder with the water in it is then immersed in a constant temperature bath at a temperature of 100°C. What is the reading for the level of water on the graduations of the cylinder after the water and the cylinder reach thermal equilibrium with the bath? The volume coefficient of expansion of water is 2.07 × 10 -4 K -1, and the linear coefficient of expansion of aluminum is 23.0 × 10 -6 K -1. 305.0 cc 303.5 cc 304.5 cc 304.0 cc 303.3 cc
Answer:
304.42 cc
Explanation:
When the aluminum expands the markings will be further apart. If the 300 cc mark was at a distance l0 of the origin at 20 C, at 100 C it will be
l = l0 * (1 + a * (t - t0))
l = l0 * (1 + 23*10^-6 * (100 - 20))
l = l0 * 1.0018
The volume of water would have expanded by
V = V0 (1 + a * (t - t0))
V = 300 (1 + 2.07*10^-4 * (100 - 20))
V = 304.968 cc
Since the markings expanded they would measure
304.968/1.0018 = 304.42 cc
A household refrigerator with a COP of 1.2 removes heat from the refrigerated space at a rate of 60kJ/min. Determine: (a) The electric power consumed by the refrigerator, and (b) The rate of heat transfer to the kitchen air.
Answer:
a) Power =50 KJ/min
b)Rate of heat transfer = 110 KJ/min
Explanation:
Given that
COP = 1.2
Heat removed from space Q = 60 KJ/min
As we know that COP of refrigerator is the ratio of heat removed to work input.
Lets take power consume by refrigerator is W
So
COP= Q/W
1.2=60/W
W=50 KJ/min
So the power consume is 50 KJ/min.
From first law of thermodynamic
Heat removed from the kitchen = 50 + 60 KJ/min
Heat removed from the kitchen =110 KJ/min
Please define the specific heat of material?
Answer and Explanation:
SPECIFIC HEAT :
Specific heat is denoted by [tex]c_v[/tex]It is the heat required for increasing the temperature of a substance which has mass of 1 kg.Its SI unit is joule/kelvinIt is physical property It can be calculated by [tex]c_v=\frac{Q}{m\Delta T}[/tex], here Q is heat energy m is mass of gas and [tex]\Delta T[/tex] is change in temperature.We discover a nearby star with two planets. The first planet has an orbit period of 10 years and is in a circular orbit with radius 106 km. The second planet has an orbit period of 15 years. What is its orbit radius? You may assume it is also in a circular orbit.
Answer: 139 Km.
Explanation:
The question tells us that a planet A has an orbit period of 10 years and its circular orbit has a radius of 106 Km, whilst a planet B has an orbit period of 15 years (also assuming a circular orbit), both orbiting a nearby star.
This information allow us to use the Kepler's 3rd law, for the special case in which the orbit is circular.
Kepler's 3rd law, tells that there exist a direct proportionality between the square of the orbit period, and the cube of the orbit radius (in the more general case, with the cube of the semi-major axis of the elipse), for celestial bodies orbiting a same star.
(like Earth and Mars orbiting Sun).
So, for planet A and planet B (orbiting a same star), we can write the following:
(TA)²/ (TB)² = (rA)³ / (rB)³
Replacing by TA= 10 years, TB= 15 years, rA= 106 Km, and solving for Rb, we get RB= 139 Km.
Do a summary what happen to titanic in the aspect of material(body) and the ductile brittle temperature (DBT) of the material.
Explanation:
A ductile material can convert into brittle material due to following reasons
1.At very low temperature
2.Due to presence of notch
In titanic ,the base of ship strike to the large ice cube and lower part of titanic ship material was made of steel .We know that steel is ductile material and when steel came with very low temperature of ice due to this ductile material converted in to brittle material and titanic ship failed.Brittle material does not show any indication before failure.
An insulated rigid tank contains 5 kg of a saturated liquid-vapor mixture of water at a. Initially, three-quarters of the mass is in the liquid phase. An electric resistor placed in the tank is connected to a 110-V source, and a current of 8 A flows through the resistor when the switch is turned on. (a) Determine how much time it will take to vaporize all the water in the tank, and (b) show the process on a T-v diagram with respect to the saturation lines.
Answer:
2.67 hours
Explanation:
If three quarters of the mass are in liquid phase, I have a mass of water:
m1 = 3/4 * 5 = 3.75 kg
The latent heat of vaporization of water is of
ΔHvap = 2257 kJ/kg
The heat needed to vaporize it is:
Q = m * ΔHvap
Q = 3.75 * 2257 = 8464 kJ
If I have a resistor connected to 110 V, with a current of 8 A, the heat it dissipates through Joule effect will be:
P = I * V
P = 8 * 110 = 880 W = 0.88 kW
With that power it will take it
t = Q / P
t = 8464/0.88 = 9618 s = 160 minutes = 2.67 hours2.
How much power would you need to cool down a closed, 1 Liter container of water from 100°C to 20°C in 5 minutes? (a) 1.1W (b)1.1kW (c)67kW (d)334 kJ
Answer:
The power required to cool the water is 1.11Kw.
Hence the correct option is (b).
Explanation:
Power needed to cool down is equal to heat extract from the water.
Given:
Volume of water is 1 liter.
Initial temperature is 100C.
Final temperature is 20C.
Time is 5 minutes.
Take density of water as 100 kg/m3.
Specific heat of water is 4.186 kj/kgK.
Calculation:
Step1
Mass of the water is calculated as follows:
[tex]\rho=\frac{m}{V}[/tex]
[tex]1000=\frac{m}{(1l)(\frac{1m^{3}}{1000l})}[/tex]
m=1kg
Step2
Amount of heat extraction is calculated as follows:
[tex]Q=mc\bigtriangleup T[/tex]
[tex]Q=1(4.186kj/kgk)(\frac{1000 j/kgk}{1 kj/kgk})\times(100-20)[/tex]
Q=334880 j.
Step3
Power to cool the water is calculated as follows:
[tex]P=\frac{Q}{t}[/tex]
[tex]P=\frac{334880}{(5min)(\frac{60s}{1min})}[/tex]
P=1116.26W
or
[tex]P=(1116.26W)(\frac{1Kw}{1000 W})[/tex]
P=1.11 Kw.
Thus, the power required to cool the water is 1.11Kw.
Hence the correct option is (b).
Convert each of the following to three significant figures: (a) 20 lb.ft to N.m, (b) 450 Ib/ft^3 to kN/m^3, and (c) 15 ft/h to mm/s.
Answer:
(a)27.12 N-m (b) 69.96 [tex]KN/m^3[/tex] (c) 1.27 mm/sec
Explanation:
We have to convert
(a) 20 lb-ft to N-m
We know that 1 lb = 4.45 N
So 20 lb = 20×4.45 = 89 N
1 feet = 0.3048 m
So [tex]20lb-ft=20\times 4.45N\times 0.3048N=27.12N-m[/tex]
(b) 450 [tex]lb/ft^3[/tex] to KN/[tex]m^3[/tex]
We know that 1 lb = 4.45 N = 0.0044 KN
[tex]1ft^3=0.0283m^3[/tex]
So [tex]450lb/ft^3=\frac{450\times 0.0044KN}{0.0283m^3}=69.96KN/m^3[/tex]
(c) 15 ft/hr to mm/sec
We know that 1 feet = 0.3048 m = 304.8 mm
And 1 hour = 60×60=3600 sec
So [tex]15ft/h=\frac{15\times 304.8mm}{3600sec}=1.27 mm/sec[/tex]
Answer:
a)20 lb.ft=27.2 N.m
b)[tex]450\dfrac{lb}{ft^3}=70.65\dfrac{KN}{m^3}[/tex]
c)15 ft/h = 1.26 mm/s
Explanation:
a)
As we know that
1 ft.lb= 1.36 N.m
So 20 lb.ft = 1.36 x 20 N.m
20 lb.ft=27.2 N.m
b)
We know that
[tex]1\dfrac{lb}{ft^3}=0.157\dfrac{KN}{m^3}[/tex]
So
[tex]450\dfrac{lb}{ft^3}=450\times 0.157\dfrac{KN}{m^3}[/tex]
[tex]450\dfrac{lb}{ft^3}=70.65\dfrac{KN}{m^3}[/tex]
c)
As we know that
1 ft/h=0.084 mm/s
So
15 ft/h = 0.084 x 15 mm/s
15 ft/h = 1.26 mm/s
In a tensile test on a steel specimen, true strain is 0.171 at a stress of 263.8 MPa. When true stress is 346.2 MPa, true strain is 0.226. Determine strain hardening exponent, n, in the flow curve for the plastic region of this steel.
Answer:n=0.973
Explanation:
Given
When True strain[tex]\left ( \epsilon _T_1\right )=0.171[/tex]
at [tex]\sigma _1=263.8 MPa[/tex]
When True stress[tex]\left ( \sigma _2\right )[/tex]=346.2 MPa
true strain [tex]\left ( \epsilon _T_2\right )[/tex]=0.226
We know
[tex]\sigma =k\epsilon ^n [/tex]
where [tex]\sigma [/tex]=True stress
[tex]\epsilon [/tex]=true strain
n=strain hardening exponent
k=constant
Substituting value
[tex]263.8=k\left ( 0.171\right )^n------1[/tex]
[tex]346.2=k\left ( 0.226\right )^n-----2[/tex]
Divide 1 & 2 to get
[tex]\frac{346.2}{263.8}=\left ( \frac{0.226}{0.171}\right )^n[/tex]
[tex]1.312=\left ( 1.3216\right )^n[/tex]
Taking Log both side
[tex]ln\left ( 1.312\right )=nln\left ( 1.3216\right )[/tex]
n=0.973
Describe the differences between convection and thermal radiation.
Answer:
Explanation:
Convection needs a fluid to transport the heat, while radiation doesn't.
Generally convection transports a lot more heat than radiation.
Since fluids tend to expand, when in a gravitational field such as that of Earth convection tends to move heat upwards while radiation is indifferent to gravity.
Specific internal energy is measured in energy per unit mass dimensions. What is 310 kJ/kg in Btu/lbm units?
Answer:
133.276 Btu/lbm
Explanation:
1 kJ/kg = 0.429923 Btu/lbm
Therefore, 310 kJ/kg = 133.276 Btu/lbm
Specific internal energy can be defined as the internal energy (kJ or Btu) divided by a unit of mass (kg or lbm). Both sets of units (kJ/kg and Btu/lbm) are units for specific energy.
Energy is an object's ability to do work and is represented in this example in Joules (J) or British Thermal Units (Btu).
1 kJ = 1000 J
Mass tells us how much something weighs and is represented in this example in kg or lbm (pounds).
The absolute pressure of an automobile tire is measured to be 320 kPa before a trip and 349 kPa after the trip. Assuming the volume of the tire remains constant at 0.022 m^3, determine the percent increase in the absolute temperature of the air in the tire. The percent increase in the absolute temperature of the air in the tire is_____ %.
Answer:
9%
Explanation:
An ideal gas is one that has its molecules widely dispersed and does not interact with each other, studies have shown that air behaves like an ideal gas, so the state change equation for ideal gases can be applied.
P1V1T2 = P2V2T1
where 1 corresponds to state 1 = 320kPa
and 2 is state 2 = 349kPa.
Given that the volume remains constant the equation is:
P1T2=P2T1
SOLVING for T2/T1
[tex]\frac{T2}{T1} =\frac{P2}{P1} =\frac{349}{320} =1.09\\\\[/tex]
The equation to calculate the percentage increase is as follows
%ΔT=[tex]\frac{(T2-T1)100}{T1} =(\frac{T2}{T1} -1)100=(1.09-1)100=(0.09)100=9%[/tex]
The pressure and temperature at the beginning of compression of a cold air-standard Diesel cycle are 100 kPa and 300K, respectively. At the end of the heat addition, the pressure is 7.2 MPa and the temperature is 2250 K. Assume constant specific heats evaluated at 300 K. Determine the cut-off ratio. There is a +/- 5% tolerance.
Answer:
Cut off ratio=2.38
Explanation:
Given that
[tex]T_1=300K[/tex]
[tex]P_1=100KPa[/tex]
[tex]P_2=P_3=7200KPa[/tex]
[tex]T_3=2250K[/tex]
Lets take [tex]T_1[/tex] is the temperature at the end of compression process
For air γ=1.4
[tex]\dfrac{T_2}{T_1}=\left(\dfrac{P_2}{P_1}\right)^{\dfrac{\gamma -1}{\gamma}}[/tex]
[tex]\dfrac{T_2}{300}=\left(\dfrac{7200}{100}\right)^{\dfrac{1.4-1}{1.4}}[/tex]
[tex]T_2=1070K[/tex]
At constant pressure
[tex]\dfrac{T_3}{T_2}=\dfrac{V_3}{V_2}[/tex]
[tex]\dfrac{2550}{1070}=\dfrac{V_3}{V_2}[/tex]
[tex]\dfrac{V_3}{V_2}=2.83[/tex]
So cut off ratio
[tex]cut\ off\ ratio =\dfrac{V_3}{V_2}[/tex]
Cut off ratio=2.38
A round steel bar, 0.02 m in diameter and 0.40 m long, is subjected to a tensile force of 33,000 kg. Y=E= 2E10 kg/m^2. (modulus).Calculate the elongation in meters.
The elongation of the steel bar under the given tensile force is approximately 2.10 millimeters.
The cross-sectional area (A) of the steel bar can be calculated using the formula for the area of a circle:
A = π * r²
Now, let's calculate A:
A = π * (0.01 m)²
≈ π * (0.0001 m²)
≈ 0.000314 m²
Now, we can calculate the elongation (ΔL) using Hooke's Law:
ΔL = (F * L) / (A * E)
Given:
F = 33,000 kg
L = 0.40 m
E = 2 * 10¹⁰ kg/m²
Now, plug in the values:
ΔL = (33,000 kg * 0.40 m) / (0.000314 m² * 2 * 10₈⁰ kg/m²)
Now, perform the calculation
ΔL ≈ (13,200 kg*m) / (6.28 * 10 kg/m²)
ΔL ≈ 2.10 * 10⁻₀ meters
What is centrifugal force with respect to unbalance? What is the formula used to determine centrifugal force?
Answer:
[tex]F = \frac{m * v^2}{r}[/tex]
Explanation:
Once the centrifugal forces are equivalent as an object rotates, it is called "in equilibrium." If the point of impact of the moving object does not align with the center of the rotation, unequal centrifugal forces are produced and the rotating component is "out of equilibrium."
Two conditions for balanced condition are: static and coupled. Static equilibrium relates to a one plane mass in which the unit is balanced by weight inverse the unbalanced mass
formula used to calculate centrifugal mass is [tex]F = \frac{m * v^2}{r}[/tex]
where, m is mass, v is speed of body. r is radius
If the local atmospheric pressure is 14.6 psia, find the absolute pressure (in psia) in a column of glycerin (rho = 74.9 lbm/ft^3) at depth of 27in.
Answer:
52.2538 psia
Explanation:
The absolute pressure at depth of 27 inches can be calculated by:
Pressure = Local pressure + Gauge pressure
Also,
[tex]P_{gauge}=\rho\times g\times h[/tex]
Where,
[tex]\rho[/tex] is the density of glycerin ([tex]\rho=74.9\ lbm/ft^3[/tex])
g is the gravitational acceleration = 32.1741 ft/s²
h = 27 in
Also, 1 in = 1/12 ft
So,
h = 27 / 12 ft = 2.25 ft
So,
[tex]P_{gauge}=74.9\times 32.1741\times 2.25\ lbf/ft^2=5422.1402\ lbf/ft^2[/tex]
Also,
1 ft = 12 inch
1 ft² = 144 in²
So,
[tex]P_{gauge}=5422.1402\ lbf/ft^2=\frac {5422.1402\ lbf}{144\ in^2}=37.6538\ lbf/in^2=37.6538\ psia[/tex]
Local pressure = 14.6 psia
So,
Absolute pressure = 14.6 psia + 37.6538 psia=52.2538 psia
A satellite would have a mass of 270 kg on the surface of Mars. Determine the weight of the satellite in pounds if it is in orbit 15,000 miles above the surface of the Earth.
Answer:
26 lbf
Explanation:
The mass of the satellite is the same regardless of where it is.
The weight however, depends on the acceleration of gravity.
The universal gravitation equation:
g = G * M / d^2
Where
G: universal gravitation constant (6.67*10^-11 m^3/(kg*s))
M: mass of the body causing the gravitational field (mass of Earth = 6*10^24 kg)
d: distance to that body
15000 miles = 24140 km
The distance is to the center of Earth.
Earth radius = 6371 km
Then:
d = 24140 + 6371 = 30511 km
g = 6.67*10^-11 * 6*10^24 / 30511000^2 = 0.43 m/s^2
Then we calculate the weight:
w = m * a
w = 270 * 0.43 = 116 N
116 N is 26 lbf
The velocity of a particle along the s-axis is given by v = 14s^7/6 where s is in millimeters and v is in millimeters per second. Determine the acceleration when s is 5.5 millimeters.
Answer:
The acceleration is [tex]2220.00m/s^{2}[/tex]
Explanation:
We know that the acceleration is given by
[tex]a=v\frac{dv}{ds}........................(i)[/tex]
The velocity as a function of position is given by [tex]v=14\cdot s^{7/6}[/tex]
Thus the acceleration as obtained from equation 'i' becomes
[tex]a=14\cdot s^{7/6}\times \frac{d}{ds}(14\cdot s^{7/6})\\\\a=14\cdot s^{7/6}\times \frac{7}{6}\times 14\cdot s^{1/6}\\\\a=\frac{686}{3}\cdot s^{8/6}[/tex]
Hence acceleration at s = 5.5 equals
[tex]a(5.5)=\frac{686}{3}\times (5.5)^{8/6}\\\\\therefore a=2220.00mm/s^{2}[/tex]
How does fouling affects the performance of a heat exchanger?
Answer:
Fouling :
When rust or undesired material deposit in the surface of heat exchanger,is called fouling of heat exchanger.
Effect of heat exchanger are as follows"
1.It decreases the heat transfer.
2.It increases the thermal resistance.
3.It decreases the overall heat transfer coefficient.
4.It leads to increase in pressure drop.
5.It increases the possibility of corrosion.
A car enters a circular off ramp (radius of 180 m) at 30 m/s. The car's on - bond accelerometers sense a total acceleration magnitude of 7.07 m/s2. What is the car's acceleration magnitude a2 (the component tangent to its path)?
Answer:
Horizontal acceleration will be [tex]2.07m/sec^2[/tex]
Explanation:
We have given radius of track = 180 m
velocity = 30 m/sec
Total acceleration [tex]a_t=7.07m/sec^2[/tex]
The centripetal;l acceleration which is always normal to the velocity also known as normal acceleration is given by [tex]a_n=\frac{v^2}{r}=\frac{30^2}{180}=5m/sec^2[/tex]
So the tangent acceleration will be [tex]a_t=7.07-5=2.07m/sec^2[/tex]
Is refrigerator with an ice-maker an open or a closed system? Explain your answer
Answer:
Open system
Explanation:
In refrigerator there is a interaction between refrigerator and environment.
In refrigerator heat moves from the system to the outer environment means there is transfer of heat from one system to environment.
We know that whenever there is transfer of energy or mass from system then it is known as pen system
So refrigerator is a open system
The boiler pressure is 38bar and the condenser pressure 0.032 bar.The saturated steam is superheated to 420 oC before entering the turbine. a) Calculate the cycle efficiency of the Rankine cycle. b) Calculate the work ratio of the Rankine cycle.
Answer:
a)38.65%
b)1221KJ/kg
Explanation:
A rankine cycle is a generation cycle using water as a working fluid, when heat enters the boiler the water undergoes a series of changes in state and energy until generating power through the turbine.
This cycle is composed of four main components, the boiler, the pump, the turbine and the condenser as shown in the attached image
To solve any problem regarding the rankine cycle, enthalpies in all states must be calculated using the thermodynamic tables and taking into account the following.
• The pressure of state 1 and 4 are equal
• The pressure of state 2 and 3 are equal
• State 1 is superheated steam
• State 2 is in saturation state
• State 3 is saturated liquid at the lowest pressure
• State 4 is equal to state 3 because the work of the pump is negligible.
Once all enthalpies are found, the following equations are used using the first law of thermodynamics
Wout = m (h1-h2)
Qin = m (h1-h4)
Win = m (h4-h3)
Qout = m (h2-h1)
The efficiency is calculated as the power obtained on the heat that enters
Efficiency = Wout / Qin
Efficiency = (h1-h2) / (h1-h4)
first we calculate the enthalpies in all states
h1=3264kJ/Kg
h2=2043kJ/Kg
h2=h3=105.4kJ/Kg
a)we use the ecuation for efficiency
Efficiency = (h1-h2) / (h1-h4)
Efficiency = (3264-2043) / (3264-105.4)
=0.3865=38.65%
b)we use the ecuation for Wout
Wout = m (h1-h2)
for work ratio=
w = (h1-h2)
w=(3264-2043)=1221KJ/kg