Answer:
• specific heat
1 Answer. The specific heat is the amount of heat required to raise the temperature of 1 g of substance by one degree Celsius or one Kelvin
For an electrical project in a residence, the electrical engineer had resistors
resistances equal to 300 and 100 to assemble a circuit of an electrical appliance that must be connected 12
hours per day. In order to obtain a chain for optimal operation, he came to the conclusion that the best
configuration would be the one shown in the figure below (consider the middle thread as ideal). Knowing that
kWh value is $ 0.35, what is the amount that must be paid for energy consumption over 1 month (30 days)?
Answer:
$ 0.077
Explanation:
We'll begin by calculating the equivalent resistance of the three 300 Ω resistors connected in series. This can be obtained as follow:
Equivalent resistance of the three 300 Ω (R₃₀₀) = 300 + 300 + 300
= 900 Ω
Next, we shall determine the equivalent resistance of the two 100 Ω resistors connected in series. This can be obtained as follow:
Equivalent resistance of the two 100 Ω (R₁₀₀) = 100 + 100
= 200 Ω
Next, we shall determine the equivalent resistance in the circuit. This can be obtained as follow:
Equivalent resistance of the three 300 Ω (R₃₀₀) = 900 Ω
Equivalent resistance of the two 100 Ω (R₁₀₀) = 200 Ω
Equivalent Resistance (R) =?
R = R₃₀₀ × R₁₀₀ / R₃₀₀ + R₁₀₀ (since they are in parallel connections)
R = 900 × 200 / 900 + 200
R = 163.64 Ω
Next, we shall determine the energy in KWh. This can be obtained as follow:
Voltage (V) = 10 V
Resistance (R) = 163.64 Ω
Time (t) for 30 days = 12 × 30 = 360 h
Energy (E) =?
E = V²t / R
E = 10² × 360 / 163.64
E = 100 × 360 / 163.64
E = 36000 / 163.64
E = 220 Wh
Divide by 1000 to express in KWh
E = 220 Wh / 1000 = 0.22 KWh
Finally, we shall determine the amount paid for 1 month (30 days). This can be obtained as follow:
Cost per KWh = $ 0.35
Energy (E) = 0.22 KWh
Cost for 30 days =?
Cost for 30 days = Energy × Cost per KWh
Cost for 30 days = 0.22 × 0.35
Cost for 30 days = $ 0.077
Therefore, the amount that must be paid for 1 month is $ 0.077
Write the differential equation that governs the motion of the damped mass-spring system, and find the solution that satisfies the initial conditions specified. Units are mks;
????
is the damping coefficient, with units of kg/sec.
m
This question is incomplete, the complete question is;
Write the differential equation that governs the motion of the damped mass-spring system, and find the solution that satisfies the initial conditions specified. Units are mks; γ is the damping coefficient, with units of kg/sec
m = 0.2, γ = 1.6 and k = 4
Initial displacement is 1 and initial velocity is -2
x" + _____ x' ____x = 0
x(t) =
Answer:
the solution that satisfies the initial conditions specified is;
x(t) = [tex]c_1e^{-4t}cos(2t)[/tex] + [tex]c_2e^{-4t}sin(2t)[/tex]
Explanation:
Given the data in the question ;
m = 0.2, γ = 1.6, k = 4
x(0) = 1, x'(0) = -2
Now, the differential equation that governs the motions of spring mass system is;
mx" + γx' + kx = 0
so we substitute
0.2x" + 1.6x' + 4x = 0
divide through by 0.2
x" + 8x' + 20x = 0
hence, characteristics equation will be;
m² + 8m + 20 = 0
we find m using; x = [ -b±√(b² - 4ac) ] / 2a
m = [ -8 ± √((8)² - 4(1 × 20 )) ] / 2(1)
m = [ -8 ± √( 64 - 80 ) ] / 2
m = [ -8 ± √-16 ) ] / 2
m = ( -8 ± 4i ) / 2
m = -4 ± 2i
Hence, the general solution of the differential equation is;
x(t) = [tex]c_1e^{-4t}cos(2t)[/tex] + [tex]c_2e^{-4t}sin(2t)[/tex]
From the initial conditions;
c₁ = 1, c₂ = 1
the solution that satisfies the initial conditions specified is;
x(t) = [tex]c_1e^{-4t}cos(2t)[/tex] + [tex]c_2e^{-4t}sin(2t)[/tex]
How long does it take for a 3.5 kW electric water heater to heat 40 kg of water? from 20 ° C to 75 ° C? The specific heat capacity of water is 4190 J/kgK PLEASE HURRY ITS A TEST
Answer:
2633.7 s
Explanation:
From the question,
Heat lost by the water heater = Heat gained by the water
Applying,
P = cm(t₂-t₁)/t.................. Equation 1
Where P = power of the heat, c = specific heat capacity of water, m = mass of water, t₁ = initial temperature, t₂ = final temperature, t = time
make t the subject of the equation
t = cm(t₂-t₁)/P.............. Equation 2
From the question,
Given: c = 4190 J/kgK, P = 3.5 kW = 3500 W, m = 40 kg, t₁ = 20°C, t₂ = 75°C
Substitute these values into equation 2
t = 4190×40(75-20)/3500
t = 9218000/3500
t = 2633.7 s
12)A black body is heated from 27°C to 127° C. The ratio of their energies of radiations emitted will be
a)3:4
c)27:64
b)9:16
d)81:256
Answer:
[tex]81:256[/tex].
Explanation:
Let [tex]T[/tex] denote the absolute temperature of this object.
Calculate the value of [tex]T[/tex] before and after heating:
[tex]T(\text{before}) = 27 + 273 = 300\; \rm K[/tex].
[tex]T(\text{after}) = 127 + 273 = 400\; \rm K[/tex].
By the Stefan-Boltzmann Law, the energy that this object emits (over all frequencies) would be proportional to [tex]T^4[/tex].
Ratio between the absolute temperature of this object before and after heating:
[tex]\displaystyle \frac{T(\text{before})}{T(\text{after})} = \frac{3}{4}[/tex].
Therefore, by the Stefan-Boltzmann Law, the ratio between the energy that this object emits before and after heating would be:
[tex]\displaystyle \left(\frac{T(\text{before})}{T(\text{after})}\right)^{4} = \left(\frac{3}{4}\right)^{4} = \frac{81}{256}[/tex].
The illustration shows ?
A)open circuit
B)broken circuit
C)series circuit
D)parallel circuit
Answer:
D)parallel circuit
Explanation:
the components are placed parallel from eachother
The diagram below shows a person swinging a hammer.
Which position has the least amount of kinetic energy?
A-1
B-2
C-3
D-4
A bird is standing on an electric transmission line carrying 3000 A of current. A wire like this has about 3.0 x 10-5 22 of resistance per meter. The bird's feet are 6 cm apart. The bird itself has a resistance of about 4 x 105 12. The bird experiences a potential difference of 0.0054 V. What current goes through the bird?
Answer:
13.5 x 10^-9 A
Explanation:
Yes
A boat that can travel at 4.60 km/h in still water crosses a river with a current of 1.80 km/h. At what angle must the boat be pointed upstream to travel straight across the river
Answer:
The angle the boat must be pointed upstream is 69⁰
Explanation:
Check the image uploaded for the diagram;
Given;
speed of the boat on still water, = 4.6 km/h
speed of the boat on a river with current, = 1.8 km/h
The angle the boat must be pointed upstream is calculated as follows
[tex]tan(\theta) = \frac{4.6}{1.8} \\\\tan(\theta) = 2.556\\\\\theta = tan^{-1}(2.556)\\\\\theta = 68.63^0\\\\\theta = 69^0[/tex]
is burning trash a physical change or chemical change?
A certain organ pipe, open at both ends, produces a fundamental frequency of 288 Hz in air. Part A If the pipe is filled with helium at the same temperature, what fundamental frequency tHe will it produce
Answer:
773.25 Hz
Explanation:
Concept : In an open organ pipe in fundamental mode of vibration
wave length of wave λ = 2L
where L is length of the pipe
frequency = velocity of sound / λ
Given values: fundamental frequency = 288 Hz
fluid is air. velocity of sound = 340 m/s
⇒ 288 = 340/2L
⇒L = 59.02 cm
The point to be noted is if the pipe is filled with helium initially at the same temperature, there would be change in the sound velocity .Then, frequency of note produced will also be changed .
We know that velocity of sound is inversely proportional to square root of molar mass of gas
velocity of sound in air / velocity of sound in helium = Square root of (Molar mass of Helium/ molar mass of air)
[tex]\frac{V_a}{V_{He}} = \sqrt{\frac{4}{28.8} } \\\frac{340}{V_{He}} =0.3725\\V_{He} =912.5 m/s[/tex]
Now, frequency = velocity of sound / λ
= 912.75 / (2 x 0.5902)
= 773.25 Hz
An electrical insulator is a material that:
A) contains no charge
B) does not allow electrons to flow
C) has more protons than electrons
D) must be a crystal
Answer:
Option B is appropriate for this question
True or False? To observe physical properties in matter, the matter must change into a new substance.
Which of the following means that an
image is real?
A. +do
B. +di
c. -di
D.-do
Answer:
B
Explanation:
True False: Marke each statement as true or false.
shift
1. Light intensity affects the rate of photosynthesis.
in
2. Energy is required by all organisms for life.
3. The ability of a plant to repair tissue depends on respiration.
4. The gas needed for photosynthesis is carbon dioxide (CO2).
5. Plants only carry on photosynthesis, not respiration.
6. Respiration can occur without photosynthesis.
Answer:
1) true 2) true 3) true 4) true 5) false 6) false
Explanation:
Which planet(s) in the solar system has/have retrograde orbits around the Sun?
A) Uranus
B) Venus and Uranus
C) Earth, Mars, and Saturn
D) Jupiter
Answer:B
Explanation:
A child moving at constant velocity carries a 2 N ice-cream cone 1 m across a level surface. What is the net work done on the ice-cream cone?
Answer:
2 Joule
Explanation:
Work=force *dISPLACMENT
2N*1M
2 JOUL
PLS HELP!! Our eyes perceive colors because of differences in which of the following properties of light?
Amplitude
Brightness
Wavelength
Source
Answer:
Your answer is wavelength
HELP ME PLEASEEEEEEEEEEEEEEEE
on what factors, current sensitivity voltage sensitivity of
a galvanometer depend?
Explanation:
The voltage sensitivity of a galvanometer is given by :
[tex]\dfrac{NBA}{RK}[/tex]
Where
N=Number of turns
A=Area of coil
B=Magnetic field produced in coil
K=Torsion constant of galvanometer
R=Resistance of galvanometer
The current sensitivity of a galvanometer is given by :
[tex]\dfrac{NBA}{K}[/tex]
Hence, this is the required solution.
HELP PLZ
Calculate the resistivity of a metal of length 2m at 20°C having the resistance
of 20 ohm and diameter 0.3mm?
Answer:
40*C
Explanation:
7) The coefficient of performance (COP) of a refrigerator is defined as the ratio of A) the heat removed from the inside to the heat expelled (dismissed) to the outside. B) the heat expelled (dismissed) to the outside to the heat removed from the inside. C) the heat removed from the inside to the work done to remove the heat. D) the heat expelled (dismissed) to the outside to the work done to remove the heat
Answer:
C) the heat removed from the inside to the work done to remove the heat.
Explanation:
Refrigerator is a heat engine working in reverse direction . Heat from cold source is taken out , some work is done to remove them and total heat and work energy is thrown into outside surrounding .
If q heat is taken out and W is work done to get this heat out .
coefficient of performance ( COP ) = q / W .
Hence C ) is the right choice .
is it possible to have rainbows during the fine sunny day? Explain your answer.
Answer:
As long as there is rain, a rainbow is possible. Rain is possible on a sunny day, and is known as a sunshower.The rainbow can be observed in a sunny day if the water droplets are present in air and the sun rays pass through it reaches the eye of the observer. In this situation, the observer can see a rainbow.
or
If you happened to look up at the sky this past weekend, you might have noticed a rare and beautiful sight: iridescent rainbow clouds, but not a drop of rain in sight. This phenomenon is known, fittingly, as cloud iridescence or irisation. The effect is not unlike seeing a rainbow painted on the clouds.
A sphere has a surface uniformly charged with 3.30 C. At what distance from its center is the potential 4.50 MV
Answer:
r = 6.6 x 10³ m = 6600 m
Explanation:
The potential at a distance from a charged sphere can be given as follows:
[tex]V = \frac{kq}{r}\\\\r = \frac{kq}{V}[/tex]
where,
r = distance = ?
k = Colomb Constant = 9 x 10⁹ Nm²/C²
q = charge on sphere = 3.3 C
V = potential = 4.5 MV = 4.5 x 10⁶ V
Therefore,
[tex]r = \frac{(9\ x\ 10^9\ Nm^2/C^2)(3.3\ C)}{4.5\ x\ 10^6\ V}[/tex]
r = 6.6 x 10³ m = 6600 m
A woman is 160160cm tall. What is the minimum vertical length of a mirror in which she can see her entire body while standing upright
This question is incomplete, the complete question is;
A woman is 160cm tall. What is the minimum vertical length of a mirror in which she can see her entire body while standing upright.
Hint: Consider the ray diagram below, of the rays that enable her to see her feet and the top of her head.
Use what you know about the law of reflection, together with a bit geometry.
The missing Image is uploaded along this answer below.
Answer:
the minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm
Explanation:
Given the data in the question and illustrated in the image below,
From image 2;
The distance from the woman's eyes to the top of her head is represented as b and a represent the distance from her eyes to her feet.
Therefore, since her height is 160 cm
a + b = 160 ------ let this be equation 1
i.e AD + DG = 160 cm
Now, from the same image 2, we will notice that triangle ABC and tringle CBD are similar, so
∠ABC = ∠CBD
AC = CD
since AD = a and AC + CD = A
AC = CD = a/2
Also, triangle DEF and FEG are si,ilar
∠DEF = ∠FEG
so
DF = FG
since DG = b and DF + FG = b
DF = b/2
so the minimum vertical length of a mirror in which the woman can see her entire body while standing upright will be;
⇒ a/2 + b/2
⇒ a + b / 2
from equation 1, a + b = 160
so
⇒ a + b / 2 = 160 / 2 = 80
Therefore, the minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm
The minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm.
What is the minimum vertical length?The minimum vertical length of a mirror in which she can see her entire body while standing upright is calculated as follows;
u + v = 160 cm
where;
u is the image heightv is the object heightFor mirror, u = v
2u = 160 cm
u = 160 cm/2
u = 80 cm
Learn more about image height here: https://brainly.com/question/10501143
#SPJ5
A system has two possible energy states, E0 and E1 (with E1 > E0). If the difference between these energy states grows (E0 and E1 get further apart while the temperature stays constant), then the ratio of the number of particles in state E0 over the number of particles in state E1 will:__________
Answer:
The number of particles in state E0 over the number of particles in state E1 will reduce
Explanation:
E0 represents the ground level state when all the particles have same energy level.
E1 represents excited state in which only a few particle reaches
E0 and E1 get further apart means that the energy difference between the two level increases.
Thus, the number of particles in state E0 over the number of particles in state E1 will reduce.
A magnetic field of 0.27 T exists in the region enclosed by a solenoid that has 599 turns and a diameter of 9.29 cm. Within what period of time must the field be reduced to zero if the average magnitude of the induced emf within the coil during this time interval is to be 12.8 kV
Answer: [tex]8.54\times 10^{-5}\ s[/tex]
Explanation:
Given
The initial magnetic field is [tex]B=0.27\ T[/tex]
No of turns [tex]N=599\ \text{turns}[/tex]
Diameter of the solenoid [tex]d=9.29\ cm[/tex]
Induced EMF [tex]E=12.8\ kV[/tex]
Induced emf is the product of no of turns and rate of change of flux.
[tex]\Rightarrow E=-N\cdot \dfrac{\Delta \phi }{\Delta t}\\\\\Rightarrow E=-N\cdot \dfrac{\Delta (B\cdot A)}{\Delta t}\\\\\Rightarrow E=-NA\cdot \dfrac{\Delta B}{\Delta t}\\\\\text{Insert the values}\\\\\Rightarrow 12.8=-599\times \pi r^2\cdot \dfrac{(0-B)}{\Delta t}\\\\\Rightarrow \Delta t=\dfrac{599\times \pi \times (4.64\times 10^{-2})\times 0.27}{12.8\times 10^3} \\\\\Rightarrow \Delta t=854.71\times 10^{-7}\ s\\\\\text{Taking absolute value}\\\Rightarrow \Delta t=8.54\times 10^{-5}\ s[/tex]
After 60 days, 100g of a certain element has decayed to only 12.5g.
What is the half- life of this element?
А
30 days
B.
8 days
С
20 days
D
5 days
Answer:
8 days
Explanation:
Please help... I'm confused on what I represents in terms of solving the total current. Would variable would I be singling out?
Answer:
the researcher say hi for us the best pa the best of us are going out to eat that I can get my money toward a little bit but the best of luck to be at work by then and we will see what the status
The springs of a 1500 kg car compress 5.00 mm when its 68 kg driver gets into the driver's seat. Part A If the car goes over a bump, what will be the frequency of oscillations
Answer:
the frequency of the oscillation is 1.5 Hz
Explanation:
Given;
mass of the spring, m = 1500 kg
extention of the spring, x = 5 mm = 5 x 10⁻³ m
mass of the driver = 68 kg
The weight of the driver is calculated as;
F = mg
F = 68 x 9.8 = 666.4 N
The spring constant, k, is calculated as;
k = F/m
k = (666.4 N) / (5 x 10⁻³ m)
k = 133,280 N/m
The angular speed of the spring is calculated;
[tex]\omega = \sqrt{\frac{k}{m} } \\\\\omega = \sqrt{\frac{133280}{1500} } = 9.426 \ rad/s[/tex]
The frequency of the oscillation is calculated as;
ω = 2πf
f = ω / 2π
f = (9.426) / (2π)
f = 1.5 Hz
Therefore, the frequency of the oscillation is 1.5 Hz
what happen to the total energy of a moving object if all the applied forces are conserved
Answer:
As objects move around over time, the energy associated with them—e.g., kinetic, gravitational potential, heat—might change forms, but if energy is conserved, then the total will remain the same. Conservation of energy applies only to isolated systems.
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