The radius of curvature of both sides of a converging lens is 18 cm. One side of the lens is coated withsilver so that the inner surface is reflective. When light is incident on the uncoated side it passes throughthe lens, reflects off the silver coating, and passes back through the lens. The overall effect is that of amirror with focal length 5.0 cm. What is the index of refraction of the lens material
Answer:
n = 1.4
Explanation:
Given,
R1 = 18 cm, R2 = -18 cm
From lens makers formula
1/f = (n - 1)(1/18 + 1/18) = (n-1)/9
f = 9/(n-1)
Power, P = 1/f ( in m) = (n-1)/0.09
Now, this lens is in with conjunction with a concave mirror which then can be thought of as to be in conjunction with another thin lens
Power of concave mirror = P' = 1/f ( in m) = 2/R = 2/0.18 = 1/0.09
Net power of the combination = 2P + P' = 2(n-1)/0.09 + 1/0.09 = 1/0.05
n = 1.4
Which of the following describes an electric insulator?
O A. A material that has a low resistance and prevents charges from
moving freely
B. A material that has a low resistance and allows charges to move
freely
C. A material that has a high resistance and prevents charges from
moving freely
D. A material that has a high resistance and allows charges to move
freely
The following that describes an electric insulator are :
C. A material that has a high resistance and prevents charges from moving freely.
The following that describes an electric insulator is a material that has a high resistance and prevents charges from moving freely. The conductors exhibit low resistance, which allows for the flow of current through it freely.Thus, the correct answer is C.
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A car travels 8km in 7 minutes. Find the speed of the car.
Answer:
42.6083 mi/h
Explanation:
Given: A car travels 8km in 7 minutes.
To find: Find the speed of the car.
Formula: [tex]Speed = \frac{Distance}{Time}[/tex]
Solution: Since the formula for the speed of an object (which is the car) is speed = distance ÷ time, divide the distance (8km) by the time (7min)
Speed = 42.6083 miles per hour
3. What is the difference between breathing and respiration?
Answer:
Breathing is the biological process of inhaling and exhaling of the gases between the cells and the environment. The mechanism of breathing involves various respiratory structures such as the windpipe, lungs and nose. Respiration, on the other hand, is a chemical process that takes place in the cell.
Explanation:
Young's double slit experiment is one of the quintessential experiments in physics. The availability of low cost lasers in recent years allows us to perform the double slit experiment rather easily in class. Your professor shines a green laser (568 nm) on a double slit with a separation of 0.112 mm. The diffraction pattern shines on the classroom wall 3.5 m away. Calculate the fringe separation between the second order and central fringe.
Answer:
Y = 17.75 x 10⁻³ m = 17.75 mm
Explanation:
Using Young's Double Slit formula below:
[tex]Y = \frac{\lambda L}{d}[/tex]
where,
Y = fringe separation = ?
λ = wavelength = 568 nm = 5.68 x 10⁻⁷ m
L = distance between slits and screen = 3.5 m
d = slit separation = 0.112 mm = 1.12 x 10⁻⁴ m
Therefore,
[tex]Y = \frac{(5.68\ x\ 10^{-7}\ m)(3.5\ m)}{1.12\ x\ 10^{-4}\ m}[/tex]
Y = 17.75 x 10⁻³ m = 17.75 mm
A coil with a circular cross section having an area of has 40turns. When the coil is placed inside a 240cmmagnetic field of 2T, the maximum torque is found to be. (a) Calculate the current in the coil. 6210.xNmi(b)What work is required to rotate the coil by , if the initial orientation of the magnetic dipole moment of 180the loop is at with respect to the field B.
Answer:
Explanation:
cross sectional area A = 40 cm² = 40 x 10⁻⁴ m² , n = 40 , Magnetic field B = 2 T . Current = I .
Maximum torque = 2 x 10⁻⁶ Nm
Value of maximum torque = n B A I .
n B A I = 2 x 10⁻⁶ Nm
40 x 2 x 40 x 10⁻⁴ I = 2 x 10⁻⁶ Nm
.32 I = 2 x 10⁻⁶ Nm
I = 2 x 10⁻⁶ / 32 x 10⁻²
= .0625 x 10⁻⁴
= 6.25 x 10⁻⁶
= 6.25 μ A .
b )
Work done in rotating a coil = n B A I ( cos θ₂ - cosθ₁ )
= n B A I ( cos θ₂ - cosθ₁ )
= 2 x 10⁻⁶ ( cos 180 - cos θ )
= 2 x 10⁻⁶ ( -1 - cos θ )
= - 2 x 10⁻⁶ ( 1 + cos θ ) J .
1.) Rn-222 decays from 400 grams to 6.25 grams in 240 minutes. How long is one “half-life.
Answer:
40
Explanation:
Which of the following statements correctly describes the index of refraction of a material? Select all that apply.
The index of refraction is the ratio of the speed of light in a material to the speed of light in a vacuum.
The index of refraction of a material must be greater than 1.
The index of refraction is the ratio of the speed of light in a vacuum to the speed of light in the material.
The index of refraction of a material must be less than 1.
The index of refraction of water is less than the index of refraction of air.
Answer:
Option C and D only
Explanation:
Option A is incorrect because refractive index of a material is the ratio of speed of light in vacuum to the speed of light in a any given medium
Option B is correct as the speed of light in vacuum is always greater than the speed of light in any given medium.
Option C is correct
Option D is incorrect
Option E is incorrect because the denser the medium the more is the refractive index. Water is denser than air, hence it should have more refractive index as compared to that of air.
A 9.83 -m ladder with a mass of 20.3 kg lies flat on the ground. A painter grabs the top end of the ladder and pulls straight upward with a force of 242 N. At the instant the top of the ladder leaves the ground, the ladder experiences an angular acceleration of 1.64 rad/s2 about an axis passing through the bottom end of the ladder. The ladder's center of gravity lies halfway between the top and bottom ends. (a) What is the net torque acting on the ladder
Answer:
The net torque will be "1366.33 Nm".
Explanation:
The given values are:
Length of ladder,
[tex]\tau_{242N} = 9.83 \ m[/tex]
then,
[tex]\tau=4.92[/tex]
Mass,
= 20.3 kg
Now,
The net torque will be:
⇒ [tex]\tau_{net}=\tau_{mg}+\tau_{242}[/tex]
On putting the given values, we get
⇒ [tex]=4.92\times (-mg)+9.83\times (+242)[/tex]
⇒ [tex]=4.92\times (-21\times 9.8)+9.83\times 242[/tex]
⇒ [tex]=-1012.53+2378.86[/tex]
⇒ [tex]=1366.33 \ Nm[/tex]
QUICK RETURN MOTION IS USED IN a whAt
Answer:
A quick return motion mechanism is used in the shaper and slotter machine in which the circular motion is converted into reciprocating motion so that the slider moves forward and backwards. In the forward direction, the cutting process occurs while in return there is no such cutting.
Consider the system consisting of the box and the spring, but not Earth. How does the energy of the system when the spring is fully compressed compare to the energy of the system at the moment immediately before the box hits the ground? Justify your answer.
Answer:
the energy when it reaches the ground is equal to the energy when the spring is compressed.
Explanation:
For this comparison let's use the conservation of energy theorem.
Starting point. Compressed spring
Em₀ = K_e = ½ k x²
Final point. When the box hits the ground
Em_f = K = ½ m v²
since friction is zero, energy is conserved
Em₀ = Em_f
1 / 2k x² = ½ m v²
v = [tex]\sqrt{ \frac{k}{m} }[/tex] x
Therefore, the energy when it reaches the ground is equal to the energy when the spring is compressed.
Based on the law of conservation of energy, the elastic potential energy of the system when the spring is fully compressed is equal to the kinetic energy of the system at the moment immediately before the box hits the ground.
What is the energy in a compressed spring?The energy in a compressed spring is elastic potential energy given by the formula:
Ek = 1/2 Kx^2where
K is spring constant x is displacement of the springWhat is the kinetic energy of a body?The kinetic energy of a body is the energy the body the has due to it's motion.
Kinetic energy, KE, is givenby the formula below:
KE = 1/2mv^2How does the energy of the system when the spring is fully compressed compare to the energy of the system at the moment immediately before the box hits the ground?From the law of conservation of energy, the total energy in a closed system is conserved.
Based on this law, all the energy in the compressed spring is converted to the kinetic energy of the box just before it reaches the ground.
Therefore, the elastic potential energy of the system when the spring is fully compressed is equal to the kinetic energy of the system at the moment immediately before the box hits the ground.
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Which property describes the distance between similar points on a wave?
A. Speed
B. Wavelength
C. Period
D. Frequency
Answer:
B
Explanation:
Answer:
Explanation:
a
1. Determine the potential energy of a 2kg rock at the top of a hill that is 20m high.
2. Determine the kinetic energy of a 2000 kg roller coaster car that is moving with a speed of 25 m/s.
3. A 80kg freezer is located in an office on the 59 floor of an office building 200 meters above the ground. What is the potential energy of the freezer?
Answer:
1) 392 joules
2) 625,000 joules
3) 156,800 joules
Explanation:
Gravitational potential energy = mgh. m = mass in kg, g = acceleration due to gravity and h = height in meters.
Kinetic energy = 1/2(m)(v)^2, m = mass in kg, v = velocity in meters per second
1) P.E = 2 x 9.8 x 20 = 392 joules
2) K.E = 1/2 x 2000 x (25)^2 = 625,000 joules
3) P.E = 80 x 9.8 x 200 = 156,800 joules
Answer:
[tex]1)\:392\:\text{J}\:(400\:\text{J with one significant figure)},\\2)\:625,000\:\text{J}\:(600,000\:\text{J with one significant figure)},\\3)\:156,800\:\text{J}\:(200,000\:\text{J with one significant figure)},[/tex]
Explanation:
1. The potential energy of an object is given by [tex]PE=mgh[/tex]. Substituting given values, we have:
[tex]PE=2\cdot 9.8\cdot 20=\boxed{392\:\text{J}}[/tex]
2. The kinetic energy of an object is given by [tex]KE=\frac{1}{2}mv^2[/tex]. Substituting given values, we have:
[tex]KE=\frac{1}{2}\cdot 2000\cdot 25^2 =\boxed{625,000\: \text{J}}[/tex]
3. 1. The potential energy of an object is given by [tex]PE=mgh[/tex]. Substituting given values, we have:
[tex]PE=80\cdot 9.8\cdot 200=\boxed{156,800\:\text{J}}[/tex]
Health professionals can help those with health issues to __________.
A.
find something other than sports or exercise in which to participate
B.
match exercise programs and sports with their needs and limitations
C.
get completely well before starting any sports or exercise program
D.
find others with the same health issue so they can commiserate on their unfortunate situation
Please select the best answer from the choices provided.
A
B
C
D
Answer:
B
Explanation:
Answer:
B
Explanation:
11. A candle is placed in front of a plane mirror. The calculated value of m,
the lateral magnification, is positive. What does the positive sign indicate
about the image?
O The image is enlarged.
The image is on the same side of the mirror as the object.
The image distance is greater than the object distance.
The image is upright.
Answer: If the magnification is positive, the image is upright compared to the object; if m is negative, the image is inverted compared to the object.
(I think, I was also stuck on this question for a bit)
The positive sign indicate about the image that
b) The image is on the same side of the mirror as the object.
d) The image is upright.
What is magnification ?
Magnification is a quantification of comparing the size of the image with respect to the size of the object. It gives us information about the image in terms of how large or small is the image formed.
magnification = height of image / height of object
since , height of object is always positive as it is always kept upright hence , in order to make m positive , height of image need to be positive
also magnification = -(v/u )
v = image distance
u = object distance
u is always positive hence , in order to make m positive , v needs to be negative , which implies on the same side of the mirror as the object
correct option
b) The image is on the same side of the mirror as the object.
d) The image is upright.
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Can anybody help meh :(
A total charge of 9.0 mC passes through a cross-sectional area of a nichrome wire in 3.6s. The number of electrons passing through the cross-sectional area in 10s is
Answer:
[tex]n=1.56\times 10^{17}[/tex] electrons
Explanation:
Given that,
Total charge = 9 mC = 0.009 C
0.009 C of charge passes through a wire in 3.6 s.
Let q' is the charge that passes through it in 10 s.
So,
[tex]\dfrac{0.009 }{3.6}=\dfrac{q'}{10}\\\\q'=\dfrac{0.009 \times 10}{3.6}\\\\q'=0.025\ C[/tex]
We know that,
q = ne
Where
n is the number of electrons
So,
[tex]n=\dfrac{q}{e}\\\\n=\dfrac{0.025}{1.6\times 10^{-19}}\\\\n=1.56\times 10^{17}[/tex]
So, [tex]1.56\times 10^{17}[/tex]electrons must pass through the cross-sectional area.
How are satellites used in GPS?
to keep the International Space Station in orbit
to communicate with the International Space Station
to communicate with possible extraterrestrial life
to pinpoint specific locations on Earth
Answer:
To pinpoint specific locations on Earth
Explanation:
The satellite has a full specific view of a specific area just like other satellites do. Satellites communicate together which also communicates with your GPS to give you an accurate location where you are or where you want to be. That is how satellites are used in GPS.
Hope this helps you out :)
PLEASE HELP WITH THIS ONE QUESTION
Which of the following must be true for a current to be induced in a wire passing through a magnetic field?
A) the magnetic field and the direction of motion must be perpendicular
B) the magnetic field and direction of motion must be parallel
Answer:
A) the magnetic field and the direction of motion must be perpendicular
For a current to be induced in a wire passing through a magnetic field, the magnetic field and the direction of motion must be perpendicular. The correct option is A.
What is magnetic field?The magnetic field is the region of space where another object experiences magnetic force and the current is induced in it.
According to the Fleming's right hand rule, the direction of motion, magnetic force and magnetic field are mutually perpendicular.
Thus, the correct option is A.
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Coherent light with wavelength 591 nm passes through two very narrow slits, and the interference pattern is observed on a screen a distance of 3.00 m from the slits. The first-order bright fringe is a distance of 4.84 mm from the center of the central bright fringe. For what wavelength of light will the first-order dark fringe be observed at this same point on the screen?
Answer:
The wavelength will be "1.182 μm".
Explanation:
The given values are:
Wavelength
[tex]\lambda=591 \ nm[/tex]
or,
[tex]=591\times 10^-9 \ m[/tex]
Distance,
[tex]d = 3.00 m[/tex]
[tex]n = 1[/tex]
Distance of fringe from center,
[tex]y = 4.84 \ mm[/tex]
We have to find the wavelength of first order dark fringe,
[tex]\lambda = ?[/tex]
As we know,
⇒ [tex]y_{bright} =\frac{1\times \lambda\times L}{d}[/tex]
On putting the given values in the formula, we get
[tex]0.00484=\frac{1\times (591\times 10^{-9})\times 3}{d}[/tex]
On applying the cross multiplication, we get
[tex]\lambda = \frac{0.00484\times 000036632}{0.5\times 3}[/tex]
[tex]=1182\times 10^{-9}[/tex]
or,
[tex]=1.182 \ \mu m[/tex]
A force of 15N is action on an area with pressure of 10pa. What is the area covered?
Answer:
150
Explanation:
P=F/A
10=15/A
10*15=15/A*15
150=A
I HOPE I HELPED
PLZ MARK ME AS BRAINIEST AND GIVE IT A THANKS
What is the answer to this problem?
Answer:
The answer is A
Explanation:
An insulator doesn't have to be a metal
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Answer:
a substance which does not readily allow the passage of heat or sound.
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3. What is the force of sliding friction
between a block and the ground if the
coefficient of kinetic friction is uk = 0.17
and the block weighs 18 N?
a. 0.52 N
b. 55 N
C. 18 N
d. 3.1 N
Answer:
the force of the friction is A-0.52
A microscope has an objective lens with diameter 1.04 cm. You wish to resolve an object 9.09 micrometers in size. You are using visible light of wavelength 562 nm. Using the Rayleigh criterion, what is the distance that the objective lens must be from the object to resolve it
Answer:
L = 0.1379 m = 13.79 cm
Explanation:
The Rayleigh criterion establishes that two objects are separated when the maximum of diffraction for slits coincides with the minimum of the other point, therefore the expression for the diffraction
a sin θ = m λ
the first zero occurs when m = 1
let's use trigonometry to find the angle
tan θ = y / L
as in these experiments the angles are very small
tan θ = sin θ /cos θ = sin θ
sin θ = y / L
we substitute
a y /L = λ
In the case of circular aperture the system must be solved in polar coordinates, for which a numerical constant is introduced
a y / L = 1.22 λ
L = a y / 1.22 λ
We search the magnitudes to the SI system
a = 1.04 cm = 1.04 10⁻² m
y = 9.09 10⁻⁶ m
λ = 562 10⁻⁹ m
let's calculate
L = [tex]\frac{1.04 \ 10^{-2} \ 9.09 \ 10^{-6} }{1.22 \ 562 \ 10^{-9} }[/tex]
L = 1.379 10⁻¹ m
L = 0.1379 m = 13.79 cm
Which term refers to how often a person works out?
Answer: Frequency
Explanation: Frequency is term which best describes how often a person exercises.
Answer:
frequency
Explanation:
I took the. test
Can someone help me with this please
Answer:
yea im sorry
Explanation:
In addition to producing images, ultrasound can be used to heat tissues of the body for therapeutic purposes. An emitter is placed against the surface of the skin; the amplitude of the ultrasound wave at this point is quite large. When a sound wave hits the boundary between soft tissue and bone, most of the energy is reflected. The boundary acts like the closed end of a tube which can lead to standing waves. Suppose 0.7 MHz ultrasound is directed through a layer of tissue at a bone 0.55 cm below the surface. Remember, sound waves in the body travel at 1540 m/s. Explain.
Answer:
ΔT = 4.058 10²⁰ [tex]\frac{S_o^2}{r^2 \ c_e}[/tex]
Explanation:
In this experiment the system can be approximated as a tube with one end open and the other closed.
The open end is where the ultrasound emitter is and the closed end where the limit between the tissue and the bone is, the length of the tube is L = 0.55 cm = 5.5 10⁻³ m
a node is formed at the closed end and a belly at the open end, so the resonance has the form
λ = 4L 1st harmonic
λ = 4/3 L third harmonic
λ = 4/5 L fifth harmonic
λ = 4L / (2n + 1) n = 0, 1, 2, (2n + 1)
This wave is a standing wave therefore energy density remains in place
P = 1/2 ρ v (w S₀)²
angular velocity is related to frequency
w = 2π f
we substitute
E = P = 2π² ρ v f² S₀²
if this energy per unit area is transformed into heat
E = m c_e DT
let's use the concept of density
ρ = m / V
m = ρ V
if there are no losses in the system
½ π² ρ v f² S₀² = ρ V c_e ΔT
ΔT = [tex]\frac{\pi ^2 \ v \f^2 S_o^2}{2V \ c_e}[/tex]
When analyzing this expression the temperature increase is
* quadratic at the frequency and maximum amplitude of the wave
* proportional to the speed of the wave in the tissue
* inversely proportional to tissue volume
we can approximate the volume of the tissue to the volume of a cylinder tube
V = π r² L
ΔT = [tex]\frac{\pi \ v \ f^2 S_o^2 }{r^2 \ L \ c_e}[/tex]
we calculate
ΔT = π 1450 (0.7 10⁶)² S₀² /( r² 5.5 10-3 c_e)
ΔT = 4.058 10²⁰ [tex]\frac{S_o^2}{r^2 \ c_e}[/tex]
On a distance-time graph, the faster the object, the _______ the slope of the line. *
A.curvier
B.flatter
C.lower
D.steeper
The following words are used to describe the direction of a moving object EXCEPT... *
A. East
B. North
C.South
D. Today
Answer:
..In a distance-time graph, the slope or gradient of the line is equal to the speed of the object. The steeper the line (and the greater the gradient) the faster the object is moving. Calculate the speed of the object represented by the green line in the graph, from 0 to 3 s.
d) steeper
D)Today
For a damped oscillator with a mass of 360 g, a spring constant 130 N/m and a damping coefficient of 86 g/s, what is the ratio of the amplitude of the damped oscillations to the initial amplitude at the end of 11 cycles
Answer:
A/A₀ = 0.5106
Explanation:
To do this, we need to use several formulas and expressions. First, we need to know the period of time of the oscillator. This can be calculated using the following expression:
ω = 2π/T (1)
But angular frequency (ω) can be also be calculated using:
ω = √(k/m) (2)
Using (1) and (2), we can solve for the period T:
2π/T = √(k/m) (mass in kg)
2π/T = √(130/0.360)
2π/T = √361.11
2π/T = 19.003
T = 2π/19.003 = 0.331 s
Now, the amplitude A at a time t, is:
A = x exp(-bt/2m) (3)
At time 0, A = x. so A₀ = x
The problem states that we have 11 cycles respect to the initial amplitude, so expression (3) can be rewritten as:
A = x exp(-b(17t/2m)) using b as kg/s = 0.086 kg/s
Replacing the data we have:
A = x exp(-0.086(17*0.331)/2*0.36)
A = x exp(-0.086 * 7.815)
A = x exp(-0.6721)
A = 0.5106x (4)
Now, doing the ratio with the innitial we have:
A / A₀ = 0.5106x / x
The ratio is:
A/A₀ = 0.5106Hope this helps
At what speed is the kinetic energy of a particle twice its Newtonian value?
In which mode of heat transfer is the convection heat transfer coefficient usually higher, natural convection or forced convection?why?