Answer:
The contribution of people to the cooling load of the store is 19722.5 W
Explanation:
Total amount of customers = 225
Total amount of employees = 20
Total amount of people in the store at that instant n = 245 people
Average rate of heat generation Q = 115 W
percentage of these heat generated that is sensible heat = 70%
Sensible heat raises the surrounding temperature. Latent heat only causes a change of state.
The total heat generated by all the people in the store = n x Q
==> 245 x 115 = 28175 W
but only 70% of this heat is sensible heat that raises the temperature of the store, therefore, the contribution of people to the cooling load of the store = 70% of 28175 W
==> 0.7 x 28175 = 19722.5 W
How much work is required to carry an electron from positive terminal of 12Volt battery to negative terminal?
Answer:
Explanation:
Work required = q x V
where q is charge on electron and V is potential difference
= 1.6 x 10⁻¹⁹ x 12
= 19.2 x 10⁻¹⁹ J
Two small plastic spheres are given positive electrical charges. When they are 20.0 cm apart, the repulsive force between them has magnitude 0.200 N.
1. What is the charge on each sphere if the two charges are equal? (C)
2. What is the charge on each sphere if one sphere has four times the charge of the other? (C)
Answer:
A. 2.97x 10^-6C
B. 1.48x10^ -6 C
Explanation:
Pls see attached file
Answer:
1) +9.4 x 10^-7 C
2) +4.72 x 10^-7 C and +1.9 x 10^-6 C
Explanation:
The two positive charges will repel each other
Repulsive force on charges = 0.200 N
distance apart = 20.0 cm = 0.2 m
charge on each sphere = ?
Electrical force on charged spheres at a distance is given as
F = [tex]\frac{kQq}{r^{2} }[/tex]
where F is the force on the spheres
k is the Coulomb's constant = 8.98 x 10^9 kg⋅m³⋅s⁻²⋅C⁻²
Q is the charge on of the spheres
q is the charge on the other sphere
r is their distance apart
since the charges are equal, i.e Q = q, the equation becomes
F = [tex]\frac{kQ^{2} }{r^{2} }[/tex]
making Q the subject of the formula
==> Q = [tex]\sqrt{\frac{Fr^{2} }{k} }[/tex]
imputing values into the equation, we have
Q = [tex]\sqrt{\frac{0.2*0.2^{2} }{8.98*10^{9} } }[/tex] = +9.4 x 10^-7 C
If one charge has four times the charge on the other, then
charge on one sphere = q
charge on the other sphere = 4q
product of both charges = [tex]4q^{2}[/tex]
we then have
F = [tex]\frac{4kq^{2} }{r^{2} }[/tex]
making q the subject of the formula
==> q = [tex]\sqrt{\frac{Fr^{2} }{4k} }[/tex]
imputing values into the equation, we have
q = [tex]\sqrt{\frac{0.2*0.2^{2} }{4*8.98*10^{9} } }[/tex] = +4.72 x 10^-7 C
charge on other sphere = 4q = 4 x 4.72 x 10^-7 = +1.9 x 10^-6 C
The process of star and planet formation begins with a large cloud of gas and dust called a solar nebula. Rank the formation events that occur within a cloud from earliest to latest.
Rank from earliest to latest. To rank items as equivalent, overlap them.
A. The cloud is large, cool, and slowly rotating
B. The cloud collapses into a disk
C. Competing rotational and gravitational forces begin to flatten the cloud
D. The cloud becomes denser, heats up, and rotates faster
E. The cloud starts to contract under the influence of gravity
A, B, E , C, D
What is Nebula?A nebula is an enormous cloud of dust and gas occupying the space between stars and acting as a nursery for new stars.
Nebulae are made up of dust, basic elements such as hydrogen and other ionized gases.
Nebula Formation:
In essence, a nebula is formed when portions of the interstellar medium undergo gravitational collapse.
Mutual gravitational attraction causes matter to clump together, forming regions of greater and greater density.
The formation events that occur within a cloud from earliest to latest are:
A. The cloud is large, cool, and slowly rotating
B. The cloud collapses into a disk.
E. The cloud starts to contract under the influence of gravity
C. Competing rotational and gravitational forces begin to flatten the cloud.
D. The cloud becomes denser, heats up, and rotates faster
Therefore , The rank from earliest to latest is A, B, E , C, D
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Two parallel plates have charges of equal magnitude but opposite sign. What change could be made to increase the strength of the electric field between the plates
Answer:
The electric field strength between the plates can be increased by decreasing the length of each side of the plates.
Explanation:
The electric field strength is given by;
[tex]E = \frac{V}{d}[/tex]
where;
V is the electric potential of the two opposite charges
d is the distance between the two parallel plates
[tex]E =\frac{V}{d} = \frac{\sigma}{\epsilon _o} \\\\(\sigma = \frac{Q}{A} )\\\\E = \frac{Q}{A\epsilon_o} \\\\E = \frac{Q}{L^2\epsilon_o}[/tex]
Where;
ε₀ is permittivity of free space
L is the length of each side of the plates
From the equation above, the electric field strength can be increased by decreasing the length of each side of the plates.
Therefore, decreasing the length of each side of the plates, could be made to increase the strength of the electric field between the plates
A car starts from rest and accelerates at a constant rate after the car has gone 50 m it has a speed of 21 m/s what is the acceleration of the car
Answer:
4.41 m/s^2
Explanation:
(v_f)^2 - (v_i)^2 = 2a * change in distance
(21)^2 - (0)^2 = 2a * 50
a = (21^2)/(2*50)
a = 4.41 m/s^2
Three cars (car 1, car 2, and car 3) are moving with the same velocity when the driver suddenly slams on the brakes, locking the wheels. The most massive car is car 1, the least massive is car 3, and all three cars have identical tires. For which car does friction do the largest amount of work in stopping the car
Answer:
Car 3
Explanation:
"A power of 200 kW is delivered by power lines with 48,000 V difference between them. Calculate the current, in amps, in these lines."
Answer:
9.6×10⁹ A
Explanation:
From the question above,
P = VI.................... Equation 1
Where P = Electric power, V = Voltage, I = current.
make I the subject of the equation
I = P/V............. Equation 2
Given: P = 200 kW = 200×10³ W, V = 48000 V.
Substitute these vales into equation 2
I = 200×10³×48000
I = 9.6×10⁹ A.
Hence the current in the line is 9.6×10⁹ A.
In a single-slit diffraction experiment, the width of the slit through which light passes is reduced. What happens to the width of the central bright fringe
Answer:
It becomes wider
Explanation:
Because The bigger the object the wave interacts with, the more spread there is in the interference pattern. Decreasing the size of the opening increases the spread in the pattern.
Comparing helium atoms with nitrogen molecules at the same temperature, the helium atoms on average are moving _______ and have _______ kinetic energy.
Answer:
Helium atoms compared to nitrogen atoms are moving faster and have a greater kinetic energy.
Explanation:
The molecular velocity of a gas at room temperature is inverse proportional to the square root of its molecular mass.
The greater the molecular mass of the gas the lesser the average speed of its molecules. Comparing the molecular masses of nitrogen and helium, helium is found to have a lower molecular mass and a corresponding greater velocity.
Hence helium moves faster than nitrogen and has a higher kinetic energy than nitrogen
Find the total energy (ft-lb) of an aircraft weighing 20,000 lbs at 5,000 ft true altitude and 200 KTS true air speed. Group of answer choices
Answer:
Hello the options to your question is missing below are the options
2 x 10^8 ft-lb
15527950 ft-lb
2.8 x 10^7 ft-lb
13.55 x 10^7 ft-lb
Answer : 13.55 * 10^7 ft-Ib
Explanation:
Given data :
weight of Aircraft (p) = 20000 Ibs
height ( h ) = 5000 ft
Velocity = 200 KTS = 370 km/h ( 10277 m/s) where 1 KTS = 1185 km/h
calculate the total energy
Total energy = potential energy + kinetic energy
potential energy = mgh = p * h =20000 * 5000 = 100 * 10^6 ft-Ibs
kinetic energy = 1/2 mv^2 = 1/2 * 625 * (33709)^2 = 3551 *10^6 ft-Ibs
where ; m = p/g = 20000 / 32 = 625 Ibs
v = 10277 m/s ≈ 33709 ft/s
hence total energy = 100 * 10^6 + 3551 * 10^6 = 1355*10^7 ft-Ibs
If the direction of the position is north and the direction of the velocity is up, then what is the direction of the angular momentum
Answer:
the direction of angular momentum = EAST
Explanation:
given
Direction of position = r = north
Direction of velocity = v = up
angular momentum = L = m(r x v)
where m is the mass, r is the radius, v is the velocity
utilizing the right hand rule, the right finger heading towards the course of position vector and curl them toward direction of velocity, at that point stretch thumb will show the bearing of the angular momentum.
then L = north x up = East
In a system with only a single force acting upon a body, what is the relationship between the change in kinetic energy and the work done by the force?
Answer: W.D = 1/2mv^2
Explanation:
If an external force or a single force is acting on a body. Just like the first law of thermodynamics, the force acting on the body will cause work done on the system.
Work done = force × distance
And the work done on the body will cause the molecules of the body to experience motion and thereby producing kinetic energy.
The work done will be converted to kinetic energy.
W.D = 1/2mv^2
6) Set the battery to a value between 0.0 V and 1.5 V. Now drag the voltage meter toward the capacitor and move the red and black leads to measure the voltage. Determine the potential difference between the two plates and whether the top plate is at higher or lower voltage than the bottom plate.
Answer:
A) 1.5 v
B) Top plate is at higher voltage than the bottom plate
Explanation:
Battery value set between 0.0 V and 1.5 V
a) The potential difference between the plates
Δ V = V1( potential at top plate) - V2( potential at lower plate )
potential at top plate = 1.5 V
potential at lower plate = 0.0 V
hence potential difference = 1.5 V
b ) The top plate is always connected to the positive terminal of the DC source ( which is at a higher potential )while the bottom plate is connected to the negative terminal of the DC source ( which is at a lower potential )
hence the Top plate is at higher voltage than the bottom plate
What is the length of the x-component of the vector shown below?
9
380
х
A. 5.5
B. 30.0
O O
O C. 7.1
O D. 8.6
Answer:
x-component = 7.1
Explanation:
x-component = 9cos38 = 7.09 =7.1
Answer:
7.1
Explanation:
use cos
A charged particle is moving with speed v perpendicular to a uniform magnetic field. A second identical charged particle is moving with speed 2v perpendicular to the same magnetic field. If the frequency of revolution of the first particle is f, the frequency of revolution of the second particle is
Answer:
the frequency of revolution of the second particle is f
Explanation:
centripetal force is balanced by the magnetic force for object under magnetic field is given as
Mv²/r= qvB
But v= omega x r
Omega= 2pi x f
f= qB/2pi x M
So since frequency does not depend on the velocity.therefore the frequency of revolution of the second particle remains the same and its equal to f
A 23.3-kg mass is attached to one end of a horizontal spring, with the other end of the spring fixed to a wall. The mass is pulled away from the equilibrium position (x = 0) a distance of 17.5 cm and released. It then oscillates in simple harmonic motion with a frequency of 8.38 Hz. At what position, measured from the equilibrium position, is the mass 2.50 seconds after it is released?
a) 5.23 cm
b) 16.6 cm
c) 5.41 cm
d) 8.84 cm
e) 11.6 cm
Answer:
Option b: 16.6 cm.
Explanation:
The position of the mass at 2.50 s can be found using the simple harmonic motion equation:
[tex] x_{t} = Acos(\omega t) [/tex]
Where:
A: is the amplitude = 17.5 cm
ω: is the angular frequency = 2πf
t = 2.50 s
[tex] x_{t} = Acos(\omega t) = 17.5cos(2\pi*8.38*2.50) = 16.6 cm [/tex]
Therefore, the correct answer is option b: 16.6 cm.
I hope it helps you!
An air conditioner connected to a 103 V rms AC line is equivalent to a 20 resistance and a 1.68 inductive reactance in series. a) What is the impedance of the air conditioner
Answer:
20.07ohms
Explanation:
Impedance is defined as the opposition to the flow of current through the elements of the circuit.
Impedance for R-L AC circuit is expressed as Z = √R²+XL²
R is the resistance
XL is the inductive reactance.
Given resistance of the air condition = 20 ohms
Inductive reactance XL = 1.68 ohms
Z = √20²+1.68²
Z = √400+2.8224
Z = √402.8224
Z = 20.07 ohms
Hence the impedance of the air conditioner is 20.07ohms
When the magnet falls toward the copper block, the changing flux in the copper creates eddy currents that oppose the change in flux. The resulting braking force between the magnet and the copper block always opposes the motion of the magnet, slowing it as it falls. The rate of the fall produces a rate of flux change sufficient to produce a current that provides the braking force. If the copper is cooled with liquid nitrogen, the resistivity of the copper drops dramatically. How will this affect the speed at which the magnet falls toward the copper
Answer:
The speed at which the magnet falls through the copper block will be reduced dramatically.
Explanation:
Eddy's current are loops of electrical current induced within conductors by a changing magnetic field in the conductor. Eddy's current is proportional to the the magnetic field strength, the rate of change of flux, the area of the loop, and is inversely proportional to the resistivity of the material. Eddy currents flows perpendicularly to the magnetic field, and in closed loops within conductors.
Reducing the resistivity of the copper will increase the Eddy current on the copper, which will in turn increase the opposition to the action producing the flux change (the falling magnet through the copper block). The result is that the speed at which the magnet falls through the copper block will be reduced dramatically.
A computer has a mass of 3 kg. What is the weight of the computer?
A. 288 N.
B. 77.2 N
C. 3N
D. 29.4 N
Answer:
29.4 NOption D is the correct option.
Explanation:
Given,
Mass ( m ) = 3 kg
Acceleration due to gravity ( g ) = 9.8 m/s²
Weight ( w ) = ?
Now, let's find the weight :
[tex]w \: = \: m \times g[/tex]
plug the values
[tex] = 3 \times 9.8[/tex]
Multiply the numbers
[tex] = 29.4 \: [/tex] Newton
Hope this helps!!
best regards!!
At a fixed point, P, the electric and magnetic field vectors in an electromagnetic wave oscillate at angular frequency w . At what angular frequency does the Poynting vector oscillate at that point
Answer:
Poynting vector oscillate at a frequency of 2omega
Explanation:
This is because The poynting vector is proportional to the cross product of electric and magnetic field vectors. So Because both fields oscillate sinusoidally with frequency w, trigonometric identities show that their product is a sinusoidal function of frequency of 2w.
A 68.5kg astronaut floating motionless next to the space station throws a 2.25kg tool away from her at 3.20m/s. With what speed and direction will the astronaut begin to move?
Answer:
-0.105 m/s
Explanation:
Given that
Mass of the astronaut, m(a) = 68.5 kg
Mass of the tool, m(t) = 2.25 kg
Speed of the tool after it is thrown, v(t) = 3.20 m/s
We know that momentum of a particle,
p = mv
See the attachment for calculations
Therefore, the speed is 0.105 m/s and it moves in the opposite direction.
g a conductor consists of an infinite number of adjacent wires, each infinitely long. If there are n wires per unit length, what is the magnitude of B~
Answer:
B=uonI/2
Explanation:
See attached file
An electromagnetic ware has a maximum magnetic field strength of 10^-8 T at a specific place in vacuum. What is the intensity of the light at that place. μ0=4πx10^-7 WbA/m g
Answer:
[tex]I=1.19\times 10^{-2}\ W/m^2[/tex]
Explanation:
It is given that,
Maximum value of magnetic field strength, [tex]B=10^{-8}\ T[/tex]
We need to find the intensity of the light at that place.
The formula of the intensity of magnetic field is given by :
[tex]I=\dfrac{c}{2\mu _o}B^2[/tex]
c is speed of light
So,
[tex]I=\dfrac{3\times 10^8}{2\times 4\pi \times 10^{-7}}\times (10^{-8})^2\\\\I=1.19\times 10^{-2}\ W/m^2[/tex]
So, the intensity of the light is [tex]1.19\times 10^{-2}\ W/m^2[/tex].
What are the approximate dimensions of the smallest object on Earth that astronauts can resolve by eye when they are orbiting 275 km above the Earth
Answer:
s_400 = 16.5 m , s_700 = 29.4 m
Explanation:
The limit of the human eye's solution is determined by the diffraction limit that is given by the expression
θ = 1.22 λ / D
where you lick the wavelength and D the mediator of the circular aperture.
In our case, the dilated pupil has a diameter of approximately 8 mm = 8 10-3 m and the eye responds to a wavelength between 400 nm and 700 nm.
by introducing these values into the formula
λ = 400 nm θ = 1.22 400 10⁻⁹ / 8 10⁻³ = 6 10⁻⁵ rad
λ = 700 nm θ = 1.22 700 10⁻⁹ / 8 10⁻³-3 = 1.07 10⁻⁴ rad
Now we can use the definition radians
θ= s / R
where s is the supported arc and R is the radius. Let's find the sarcos for each case
λ = 400 nm s_400 = θ R
S_400 = 6 10⁻⁵ 275 10³
s_400 = 16.5 m
λ = 700 nm s_ 700 = 1.07 10⁻⁴ 275 10³
s_700 = 29.4 m
An electron, moving toward the west, enters a uniform magnetic field. Because of this field the electron curves upward. The direction of the magnetic field is
Answer:
The magnetic field's direction is towards the north
Explanation:
The force on a positive charge in a uniform magnetic field is represented by the right hand rule. To determine the direction of the force, place your right hand with your palm up, and your thumb at 90° to the other fingers. If the fingers represent the magnetic field, and the thumb the direction of the positive charge, then the palm will push up in the direction of the force. But a negative charge like an electron pushes in exactly the opposite direction. So if you follow this rule, you will find that the magnetic field points towards the north.
The direction of the magnetic field is towards the North. This can be
determined using the right hand rule by Fleming.
The right hand rule states that to determine the direction of the magnetic
force, the right thumb should be pointed in in the direction of the velocity,
index finger in the direction of the magnetic field and middle finger in the
direction of magnetic force.
When this is applied, we will discover that the index finger will point towards
the north region.
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A tornado passes in front of a building, causing the pressure to drop there by 25% in 1 second. Part A If a door on the side of the building is 8.1 feet tall and 3 feet wide, what is the net force on the closed door.
Answer:
F_net = 264, 26 pound
Explanation:
For this exercise we use Newton's second law
F_net = F_int - F_outside
where the force can be found from the definition of pressure
P = F / A
F = P A
we substitute
F_net = P_inside A - P_outside A
F_net = A (P_inside - P_outside)
indicate that the pressure on the outside is 25% less than the pressure on the inside
P_outside = 0.25 P_inside
The area is
A = L W
we substitute
F_net = L W P_inside (1-0.25)
let's calculate
suppose the pressure inside is atmospheric pressure
P_inside= P_atmospheric = 1,013 10⁵ Pa = 14.7 PSI
F_net = 8.1 3 14.5 0.75
F_net = 264, 26 pound
A sailor strikes the side of his ship just below the surface of the sea. He hears the echo of the wave reflected from the ocean floor directly below 2.5 ss later.
How deep is the ocean at this point? (Note: Use the bulk modulus method to determine the speed of sound in this fluid, rather than using a tabluated value.)
_____ m
Answer:
1248m
The time that wave moves from the wave source to the ocean floor is half the total travel time: t = 2.5/2 = 1.25s
The speed of sound in seawater is 1560 m/s
Therefore, s = vt = (1560 m/s)(1.25s) =1248 m = 1.2km
An astronomy student, for her PhD, really needs to estimate the age of a cluster of stars. Which of the following would be part of the process she would follow?
A. plot an H-R diagram for the stars in the cluster
B. count the number of M type stars in the cluster
C. measure the Doppler shift of a number of the stars in the cluster
D. search for planets like Jupiter around the stars in the center of the cluster
E. search for x-rays coming from the center of the cluster
Answer:
A. plot an H-R diagram for the stars in the cluster.
Explanation:
A star cluster can be defined as a constellation of stars, due to gravitational force, which has the same origin.
The astronomy student would have to plot an H-R diagram for the stars in the cluster and determine the age of the cluster by observing the turn-off point. The turn-off is majorly as a result of gradual depletion of the source of energy of the star. Thus, it projects off the constellation.
A child pulls on a wagon with a force of 75 N. If the wagon moves a total of 42 m in 3.1 min, what is the average power delivered by the child
Answer:
16.96 W
Explanation:
Power: This can be defined as the rate at which work is done by an object. The S.I unit of power is Watt(W).
From the question,
P = (F×d)/t....................... Equation 1
Where P = power, F = force, d = distance, t = time.
Given: F = 75 N, d = 42 m, t = 3.1 min = 3.1×60 = 186 s
Substitute these values into equation 1
P = (75×42)/186
P = 16.94 W
Hence the average power delivered by the child = 16.96 W
The average power delivered by the child is 16.96 W.
What is Power?Power can be defined as the rate at which work is done by an object. The S.I unit of power is Watt(W).
Work done is the product of force and displacement caused.
Then the formula of power will be
P = (F×d)/t
Substitute F = 75 N, d = 42 m, t = 3.1 min = 3.1×60 = 186 s, we get the power as
P = (75×42)/186
P = 16.94 W
Hence, the average power delivered by the child is 16.96 W.
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A container with volume 1.83 L is initially evacuated. Then it is filled with 0.246 g of N2. Assume that the pressure of the gas is low enough for the gas to obey the ideal-gas law to a high degree of accuracy. If the root-mean-square speed of the gas molecules is 192 m/s, what is the pressure of the gas?
Answer:
The pressure is [tex]P = 1652 \ Pa[/tex]
Explanation:
From the question we are told that
The volume of the container is [tex]V = 1.83 \ L = 1.83 *10^{-3 } \ m^3[/tex]
The mass of [tex]N_2[/tex] is [tex]m_n = 0.246 \ g = 0.246 *10^{-3} \ kg[/tex]
The root-mean-square velocity is [tex]v = 192 \ m/s[/tex]
The root -mean square velocity is mathematically represented as
[tex]v = \sqrt{ \frac{3 RT}{M_n } }[/tex]
Now the ideal gas law is mathematically represented as
[tex]PV = nRT[/tex]
=> [tex]RT = \frac{PV}{n }[/tex]
Where n is the number of moles which is mathematically represented as
[tex]n = \frac{ m_n }{M }[/tex]
Where M is the molar mass of [tex]N_2[/tex]
So
[tex]RT = \frac{PVM_n }{m _n }[/tex]
=> [tex]v = \sqrt{ \frac{3 \frac{P* V * M_n }{m_n } }{M_n } }[/tex]
=> [tex]v = \sqrt{ \frac{ 3 * P* V }{m_n } } }[/tex]
=> [tex]P = \frac{v^2 * m_n}{3 * V }[/tex]
substituting values
=> [tex]P = \frac{( 192)^2 * 0.246 *10^{-3}}{3 * 1.83 *10^{-3} }[/tex]
=> [tex]P = 1652 \ Pa[/tex]