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A scanning tunneling microscope is used to measure small changes in height of a surface by detecting changes in the tunneling current between the tip and the surface. The current is proportional to the tunneling coefficient (ie. I = const * T) which follows the general equation for tunneling through a square well , with C dependent on the molecule and L is the distance. The transmission coefficient at one point is T = 0.01, what is the relative current if the distance is increased from L to 5L? We are interested in I(5L)/I(L). (Note: there may be more information provided than you need to solve the problem.)
Answer:
[tex]\mathbf{\dfrac{I(5l)}{I(l) } =10^{-8}}[/tex]
Explanation:
We are being told that the current is proportional to the tunneling coefficient[tex]I(l) = I_0 e^{-2kl}[/tex] ;
where l = distance between the tip and the surface.
Let [tex]I(l) = I_0 e^{-2kl}[/tex] ------------ equation (1)
and [tex]I(5l) = I_0 e^{-2k(5l)}[/tex] ------------ equation (2)
Dividing equation (2) by (1); we have :
[tex]\dfrac{I(5l)}{I(l) } = \dfrac{I_0 e^{-2k(5l)}}{ I_0 e^{-2kl}}[/tex]
[tex]\dfrac{I(5l)}{I(l) } =e^{-2k(5-1)l}[/tex]
[tex]\dfrac{I(5l)}{I(l) } =(e^{-2kl})^4[/tex]
where ;
[tex](e^{-2kl})[/tex] represents the transmission coefficient T = 0.01
Thus; replacing the value for 0.01;we have;
[tex]\dfrac{I(5l)}{I(l) } =0.01^4[/tex]
[tex]\mathbf{\dfrac{I(5l)}{I(l) } =10^{-8}}[/tex]
An object with more mass has more kinetic energy than an object with less
mass, if both objects are moving
OA) at the same speed
OB) in the same direction
OC) in opposite directions
Explanation:
The kinetic energy of an object is given in terms of its mass and object as :
[tex]K=\dfrac{1}{2}mv^2[/tex]
An object with more mass has more kinetic energy. An object with less mass, if both objects are moving at the same speed, in opposite directions, will have less kinetic energy. The square of v will give positive number.
A student claims that water's polarity is the reason it has a high specific heat. What method could the student use to test his claim? Perform research to see if other polar molecules have high specific heat Measure how much energy it takes to increase the temperature of water by one degree Mix water with an acid and test the new specific heat Determine how dissolving salt in water affects the specific heat
Answer:
B
Explanation:
The method used by the student to test his claim is determine how dissolving salt in water affects the specific heat. The correct option is fourth.
What is specific heat?The specific heat is the amount of heat required to change the temperature by 1°C. It is denoted by C.
A student claims that water's polarity is the reason it has a high specific heat.
Polarity is determined by the salt dissolved in water. So, to determine how dissolving salt in water affects the specific heat is best method.
Thus, the fourth option is correct.
Learn more about specific heat.
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Density changes are responsible for which method of thermal energy transfer.
Answer:
convection
Explanation:
because in convection, molecules move with heat(i.e wind). So, when molecules move to another place, the mass will be reduce and the density will change
Jake, who weighs 680 newtons, climbs a 6-meter ladder in 8 seconds. What was Jake's power?
Diagram shows the heating
curve for 0.5 kg heated by a
100 W immersion heater. What
is the specific heat capacity of
the liquid?
Answer: 35
Explanation:
Given the following :
M = 0.5 kg
Power of heater = 100W
From the graph ;
Time (t) = 7seconds
Change in temperature(Dt) = t2 - t1
Where t2 = 70°C, t1 = 30°C
Dt = (70 - 30)°C = 40°C
Recall Q = iVt
IV = power
Q = mcDt
c = specific heat capacity of liquid
mcDt = ivt
mcDt = power × t
0.5 × c × 40°C = 100 × 7
20°C × c = 700 J
c = 700 J/ 20°C
c = 35 J / kg°C
what is web browser
Answer:
A web browser is a software application for accessing information on the World Wide Web
Answer:
web browser (commonly referred to as a browser) is a software application for accessing information on the World Wide Web. When a user requests a web page from a particular website, the web browser retrieves the necessary content from a web server and then displays the page on the screen.
Explanation:
what happens to the moleclues within a gas when the gas Condeenses
Which of the following technologies is based on the work of Subrahmanyan Chandrasekhar? A. Undersea fiber optic communications cables B. An orbiting observatory to detect X-rays from space objects C.Computer models to predict the effects of climate change D. Radar to detect the movement of storms
Answer:the answer is B
Explanation:
APE X
The technology that is based on the work of Subrahmanyan Chandrasekhar is an orbiting observatory to detect X-rays from space objects, therefore the correct option is B.
What is Chandrasekhar's limit?Chandrasekhar's limit is a type of maximum limited value that is used to define the maximum mass of a white dwarf star. The generally internationally considered value of the Chandrasekhar limit is about 1.44 times the mass of the sun which is approximately 2.765×10³⁰ kg.
In other words, one can say that Chandrasekhar limit is the maximum value that can attain 1.44 times the solar mass.
In other words, one can say that star with a mass more than 1.44 times that of the Sun does not form a white dwarf but continues to collapse, finally forming a neutron star
An orbiting observatory to detect X-rays from space objects is based on the principle of Chandrasekhar's limit. The correct option is B.
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Which is an example of transforming potential energy to kinetic energy? Select two options
changing thermal energy to electrical energy
changing chemical energy to thermal energy
changing nuclear energy to radiant energy
changing radiant energy to electrical energy
changing mechanical energy to chemical energ
Answer :
.changing chemical energy to thermal energy
.changing nuclear energy to radiant energy
Explanation :
Hope it helps you mate ))Answer:
.changing chemical energy to thermal energy
.changing nuclear energy to radiant energy
Explanation:
Help what is the answer
Answer:
C
Explanation:
[tex]F=k\dfrac{Q_1Q_2}{r^2}= \\\\(8.99 \times 10^9)\dfrac{(-2\times 10^{-4})(8\times 10^{-4})}{0.3^2}\approx 1.6\times 10^4 N[/tex]
Hope this helps!
A curium-242 (Z= 96) can be produced by positive-ion bombardment when an alpha particle collides with which of the following nuclei? Note: A neutron is also a product of this bombardment, in addition to the curium-242.
A. Pu -239
B. U -239
C. Am-241
D. Cf-249
E. Pu-241
Answer:
A. Pu -239
Explanation:
An isotope is an element with the same atomic number but different mass number. most isotope are unstable, having short half life.
Curium-242 is an isotope produced when Plutonium 239 is bombarded by an alpha particle. This reaction between Plutonium 239 and alpha particle gives curium-242, neutron and a high amount of energy as the products.
Curium oxidizes easily, and it is a dangerous metal which can cause cancer initiation when absorbed by biological materials e.g bones or tissue.
A car has a kinetic energy of 1.9 × 103 joules. If the velocity of the car is decreased by half, what is its kinetic energy?
Answer:
475 J
Explanation:
Kinetic energy is calculated by one half of the product of mass and velocity squared or expressed as:
KE = 1/2 (mv²)
We calculate as follows:
KE1 = 1/2 (mv²) = 1.9 * 10^3 joules
KE2 = 1/2 (m(v/2)²) = 1/2 (mv²/4)
KE2 = 1.9 * 10^3 joules / 4 = 475 J
what is mercury barometer
Explain two applications of resonance
PLEASEEEE HELP ME!
Answer:
in physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies. example a familiar example is a playground swing, which acts as a pendulum.
hope this helped!
Is a 5kg ball is rolling to the right and has a velocity of 4 m/s what is the momentum of the ball
Answer:
∆p = 20 kg * m/s
Explanation:
The change in momentum is the mass of the body multiplied by the change in its velocity.
In formula form ∆p = m * ( ∆v ).
with m = 5 kg and ∆v = 4 m/s
∆p = 5 kg * 4 m/s
∆p = 20 kg * m/s
An electric kettle is rated at 2kW. How much energy is transferred in 30s?
Answer : 60,000 Joule
✑ Given :
Power = 2 KW = 2 × 1000 W = 2000 W ( since 1 KW = 1000 W )Time taken = 30 seconds✑ To find :
Energy☞ Solution :
✾ Energy = Power × Time ✾
= 2000 × 30
= 60,000 Joule
Hope I helped!
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Answer:
60,000 Joules
Explanation:
GIVEN:
Power = 2kW = 2000 W
Time = 30 sec
REQUIRED:
Energy = ?
SOLUTION:
Power = Energy / Time
Making Energy the subject of formula
Energy = Power × Time
E = 2000 W × 30 s
E = 60,000 Joules
A wire having resistance 20 ohm is bent to make a closed square.What is the resistance across the diagonal of square?
Answer:
5 Ω
Explanation:
When it is bent into a square, each side of the square will get 5 Ω resistance. As considered diagonally ,path of the wire between to diagonal points is the two sides of the square (that is half the length of the wire connected in parallel position). Which gives 10 ohm parallel to 10 ohm wire. So it finally read as 5 Ω wire
what is the wavelength of radio waves transmitted by an FM station at 90MHz where 1M=10^6, and speed of radiowave is 3*10^8m/s
Answer:
λ = 3.33 m
Explanation:
Given:
Frequency = f = 9 × 10⁷ Hz
Speed = v = 3 × 10⁸ m/s
Required:
Wavelength = λ = ?
Formula:
v = fλ
Solution:
Putting the givens in the formula
v = fλ
λ = [tex]\frac{v}{f}[/tex]
λ = [tex]\frac{3*10^8}{9*10^7}[/tex]
λ = 0.33 × 10¹
λ = 3.33 m
The mass of an object is 50 kg. If its weight is 600N on a certain planet. Calculate the
gravitational field strength of the planet.,
Answer: The answer is 700kg
Explanation:
You are on an interstellar mission from the Earth to the 8,7 light-years distant star Sirius. Your spaceship can travel with 70% the speed of light and has a cylindrical shape with a diameter of 6 m at the front surface and a length of 25 m. You have to cross the interstellar medium with an approximated density of 1 hydrogen atom/m3 (a) Calculate the time it takes your spaceship to reach Sirius. (b) Determine the mass of interstellar gas that collides with your spaceship during the mission. Note:use 1,673x 10^-27 kg as proton mass
Answer:
Time = 12.43 years
Mass = 4.71.43kg
Explanation:
Given the following :
Distance = 8.7 light years
Speed = 70% the speed of light
Diameter = 6m
Lengtg = 25m
Density = 1 hydrogen atom/m^3
Mass of proton(Me) = 1.673x 10^-27
A.) time it takes your spaceship to reach Sirius :
From the relation: Speed = (distance / time)
Time = distance / speed
Time = (70/100) × 1 light year
Distance = 8.7 light years
Time = 8.7 / 0.7 = 12.4285 years
Time = 12.43 years
B.) Mass of inter-stellar gas that collides with the spaceship can be calcuted by finding the product of the surface area of the cylindrical space ship and the mass of proton.
That is ;
surface area * mass of proton
Surface area of a cylinder = 2πrh + πr^2×Me
= 2πrh + Me×πr^2)
=( 2 × 22/7 × 3 × 25) + (22/7 × 3^2 × 1.673 * 10^-27)
= 2× 235.714 + 28.285) × 1.673 * 10^-27
= 471.428 + 47.31 * 10^-27
= 471.428 + 4.73 × 10^-26
= 4.71.43kg approximately
Explain why a Merry-Go-Round and a Ferris Wheel have a constant acceleration when they are moving.
Answer must be at least two sentences and contain words such as velocity and acceleration.
Explanation:What is centripetal acceleration?
Can an object accelerate if it's moving with constant speed? Yup! Many people find this counter-intuitive at first because they forget that changes in the direction of motion of an object—even if the object is maintaining a constant speed—still count as acceleration.
Acceleration is a change in velocity, either in its magnitude—i.e., speed—or in its direction, or both. In uniform circular motion, the direction of the velocity changes constantly, so there is always an associated acceleration, even though the speed might be constant. You experience this acceleration yourself when you turn a corner in your car—if you hold the wheel steady during a turn and move at constant speed, you are in uniform circular motion. What you notice is a sideways acceleration because you and the car are changing direction. The sharper the curve and the greater your speed, the more noticeable this acceleration will become. In this section we'll examine the direction and magnitude of that acceleration.
The figure below shows an object moving in a circular path at constant speed. The direction of the instantaneous velocity is shown at two points along the path. Acceleration is in the direction of the change in velocity, which points directly toward the center of rotation—the center of the circular path. This direction is shown with the vector diagram in the figure. We call the acceleration of an object moving in uniform circular motion—resulting from a net external force—the centripetal acceleration
a
c
a
c
a, start subscript, c, end subscript; centripetal means “toward the center” or “center seeking”.
A tuning fork is vibrating the air around it. What best describes the waves produced by the tuning fork?
Answer:
The water particles move in the same direction as the vibrating source of the sound wave. ... What best describes the waves produced by the tuning fork? mechanical, because the vibrating tuning fork makes air molecules around it vibrate. A wave is produced in a Slinky as shown.
Explanation:
Answer:
mechanical, because the vibrating tuning fork makes air molecules around it vibrate
Explanation:
Se realiza un experimento en el que se mide el alargamiento de un muelle debido a la acción de una pesa; se trata de comprobar la ley de Hooke. Los datos que se han obtenido son: Medición 1 2 3 4 5 Alargamiento 42.0 48.4 51.3 56.3 58.6 Masa 2 4 6 8 10 El coeficiente de determinación es:
Answer:
m = 1,975 m / kg , b = 38.05 m
Explanation:
In this experiment, the elongation is plotted against the applied mass
getting a straight line
y = m x + b
where b would be the initial length of spring let's calculate the slope for which we use two well separated points
m = (56.3 -48.4) / (8 - 4)
m = 1,975 m / kg
the equation remains
y = 1,975 x + b
for x = 2 kg y = 42.0 m
we substitute in the equation
42 = 1,975 2 + b
b = 42 - 3.95
b = 38.05 m
If there are a boys pulling a rubber
with the same amount of force what will happen?
Answer:
The rubber will expand to its maximum and then tear in the middle.
Explanation:
Answer:
Hey!
Well if they continue to pull the rubber band, it would eventually rip apart right in the middle as the force could not be contained by the elastic fibres and had reached its maximum extension!
Explanation:
HOPE THIS HELPS!!
This is a physics question about acceleration, I'm a Sophmore btw
"Determine the amount of time it takes for a car to accelerate forward at a rate of 7.00 m/s^2 if it starts from rest and reaches a final speed of 30.0 m/s."
I was having trouble figuring out the time if anyone can help that'd be lovely!!
Answer:
4.29 s
Explanation:
Given:
v₀ = 0 m/s
v = 30.0 m/s
a = 7.00 m/s²
Find: t
v = at + v₀
30.0 m/s = (7.00 m/s²) t + 0 m/s
t = 4.29 s
People often think that Galileo dropped two objects of dramatically different mass off of the Leaning Tower of Pisa that both hit the ground at the same time. Explain why in reality this was most likely not true.
Answer: because of air resistance. See explanation for further details.
Explanation: Galileo performed an experiment to proof that the time of descent of two different masses is independent of time.
But in reality this is most likely not true because of air resistance and other fluid frictional effects in consideration.
If the experiment is performed in a vacuum, it will always be true that time is independent of masses of two falling objects.
What is a resistor? A. a light bulb B.a switch C. a battery
Answer:
A resistor is a battery
Answer:
The answer is A
Explanation:
A resistor is a light bulb because it is the flow of an electric current in an electric circuit.
A 1.00 kg block of ice, at -25.0°C, is warmed by 35 kJ of energy. What is the final temperature of the ice?
Answer:
-8.4°C
Explanation:
From the principle of heat capacity.
The heat sustain by an object is given as;
H = m× c× (T2-T1)
Where H is heat transferred
m is mass of substance
T2-T1 is the temperature change from starting to final temperature T2.
c- is the specific heat capacity of ice .
Note : specific heat capacity is an intrinsic capacity of a substance which is the energy substained on a unit mass of a substance on a unit temperature change.
Hence ; 35= 1× c× ( T2-(-25))
35= c× ( T2+25)
35 =2.108×( T2+25)
( T2+25)= 35/2.108= 16.60°{ approximated to 2 decimal place}
T2= 16.60-25= -8.40°C
C, specific heat capacity of ice is =2.108 kJ/kgK{you can google that}
To solve this we must be knowing each and every concept related to energy. Therefore, -8.40°C is the final temperature of the ice.
What is energy?In physics, energy is the capacity to accomplish work. It can be potential, kinetic, temperature, electrical, chemical, radioactive, or in other forms.
There is also heat and work—energy inside the process of being transferred through one body to the other. Energy is always classified according to its type once it has been transmitted. As a result, heat transported could become thermal energy, whereas labor done may emerge as mechanical energy.
H = m× c× (T2-T1)
35= 1× c× ( T2-(-25))
35= c× ( T2+25)
specific heat capacity of ice is =2.108 kJ/kgK
35 =2.108×( T2+25)
( T2+25)= 35/2.108= 16.60°
T2= 16.60-25= -8.40°C
Therefore, -8.40°C is the final temperature of the ice.
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how much energy (in kW-h) does a 900 Watt stove use in a week if it is used for 1.5 hours each day?
Answer:
9.45 kWh
Explanation:
Energy = Power × time
E = 900 W × (1.5 h/day × 7 day)
E = 9450 Wh
E = 9.45 kWh