Answer:
a) Ф = 1.79 eV here are a number of electrons expelled from the metal and these electrons are accelerated by the difference in potential and you can establish a curren
b) E = 1.14 eV the energy of the photons is less than the work function of the metal, so there are no ejected electrons and there can be no current
Explanation:
a) This is a problem about the photoelectric effect, for the current to flow there must be ejected electrons so that they can be accelerated, this effect was explained by Insistent using
h f = K - Ф
where hf is the energy of the incident photons, Ф the metal work function and K the kinetic energy of the ejected electrons, the minimum value that it can have is zero
Ф = h f
let's use the relationship
c = λ f
f = c / λ
we substitute
Ф = h c / λ
let's calculate
Ф = 6.63 10⁻³⁴ 3 10⁸/694 10⁻⁹
Ф = 2.87 10⁻¹⁹ J
let's reduce this value to units of eV
Ф = 2.87 10⁻¹⁹ J (1 eV / 1.6 10⁻¹⁹ J)
Ф = 1.79 eV
This is the maximum value that the work function can have for the electrons to be expelled, as they indicate that the work function of the anode is 1.3 eV there are a number of electrons expelled from the metal and these electrons are accelerated by the difference in potential and you can establish a current
B) The laser is changed for another λ = 1090 nm = 1090 10⁻⁹ m
Let's find the energy of the laser photons
E = h c /λ
E = 6.63 10⁻³⁴ 3 10⁸/1090 10⁻⁹
E = 1.82 10⁻¹⁹ J
we reduce to eV
E = 1.82 10⁻¹⁹ J (1 eV / 1.6 10⁻¹⁹ J)
E = 1.14 eV
In this case, the energy of the photons is less than the work function of the metal, so there are no ejected electrons and there can be no current
What comes to mind when you think of the
word energy?
Think of all of the ways that you have heard
people use that word.
Good energy, Bad energy, Energy used to run, Energy drinks,
The coordinate of a particle in meters is given by x(t)=1 6t- 3.0t , where the time tis in seconds. The
particle is momentarily at rest at t is:
Select one:
a. 9.3s
b. 1.3s
C. 0.75s
d.5.3s
e. 7.3s
Complete question:
The coordinate of a particle in meters is given by x(t)=1 6t- 3.0t³ , where the time tis in seconds. The
particle is momentarily at rest at t is:
Select one:
a. 9.3s
b. 1.3s
C. 0.75s
d.5.3s
e. 7.3s
Answer:
b. 1.3 s
Explanation:
Given;
position of the particle, x(t)=1 6t- 3.0t³
when the particle is at rest, the velocity is zero.
velocity = dx/dt
dx /dt = 16 - 9t²
16 - 9t² = 0
9t² = 16
t² = 16 /9
t = √(16 / 9)
t = 4/3
t = 1.3 s
Therefore, the particle is momentarily at rest at t = 1.3 s
give five characteristics of a metal
Answer:
are good conductors of heat,are you used to make doors utensils e.t.c.
A train running along a straight track at 32.90 m/s is slowed at a rate of 0.783 m/s/s to a stop how far did the train travel before coming to rest ?
Answer:
The distance traveled by the train is 691.2 m
Explanation:
Given;
initial velocity of the train, u = 32.9 m/s
deceleration of the train, a = - 0.783 m/s²
final velocity of the train when brought to a stop, v = 0
The distance traveled by the train is given by;
v² = u² + 2as
0 = (32.9)² + 2(-0.783)s
0 = 1082.41 - 1.566s
1.566s = 1082.41
s = 1082.41 / 1.566
s = 691.2 m
Therefore, the distance traveled by the train is 691.2 m
You are at the park with your little brother, when you notice a small merry-go-round with a radius that looks to be about 1.5 m. Your brother climbs on, and you give him a spin. From rest, you speed up smoothly, completing one full lap in 3.0 seconds. You wonder what sort of acceleration (magnitude and direction) your brother experiences at the very start of the motion, and at the very end of the first lap. He is quite young and hasn't studied any physics, so he does not know how to answer your question. You decide to give him your smartphone (which has a built-in accelerometer), and repeat the experiment. What will the smartphone record
Answer:
Explanation:
angle covered in one rotation = 2π radian
θ = ωt + 1/2 αt²
θ is angle rotated in time t with initial angular velocity of ω and angular acceleration α .
Putting the values
2π = 0 + 1/2 x α x 3²
α = 1. 4 radian / s²
linear acceleration = α x r = 1.4 x 1.5 = 2.1 m / s².
Initial acceleration = 2.1 m /s²
final angular velocity = α t = 1.4 x 3 = 4.2 radian / s
linear velocity = 4.2 x 1.5 = 6.3 m /s
centripetal acceleration = v² / R = 6.3² / 1.5 = 26.46 m /s²
radian acceleration = 26.46 m /s
tangential acceleration = 2.1 m /s²
Total final acceleration = √ ( 26.46² + 2.1² )
= √ ( 700.13 + 4.41)
Final acceleration = 26.53 m / s²
The kid will undergo a circular motion and the smartphone which has a built-in accelerometer will record the acceleration [tex]26.54 \,m/s^2[/tex], which is the magnitude of the vector sum of both radial acceleration and tangential acceleration.
Circular MotionThe angle covered in one full rotation, i.e.; the angular displacement is,
[tex]\theta = 2\pi\,\, radian[/tex]
The kinematics equation in the case of rotational motion is given by;
[tex]\theta = \omega_i \,t + \frac{1}{2} \alpha t^2[/tex]
But the initial angular velocity, [tex]\omega_i = 0[/tex]
Time taken to complete one lap is, [tex]t = 3\,s[/tex]
Therefore, substituting the given values in the kinematics equation;
[tex]2\pi \;rad=0 + \frac{1}{2} \alpha\times (3)^2[/tex]
[tex]\implies \alpha = \frac{4 \pi\,\,rad}{9\,s^2} =1.395\,rad/s^2 \approx 1.4\,rad/s^2[/tex]
We know that linear acceleration (here tangential direction) is given by,
[tex]a_T=a = r \alpha = 1.5\,m \times 1.4\; rad/s^2=2.1\,m/s^2[/tex]
Also, the final angular velocity after 3 s is given by;
[tex]\omega_f = \alpha t=1.4\,rad/s^2 \times 3\,s = 4.2\,rad/s[/tex]
Therefore, the final linear velocity is;
[tex]v_f = r \omega = 1.5\,m \times 4.2\,rad/s = 6.3\,m/s[/tex]
We know that the centripetal or the radial acceleration is given by;
[tex]a_r = \frac{v^2}{r} = \frac{(6.3\,m/s)^2}{1.5m}=26.46\,m/s^2[/tex]
Therefore, the total acceleration is given by;
[tex]a_{total} = \sqrt{(a_T)^2 + (a_r)^2\,} =\sqrt{(2.1)^2 + (26.46)^2} =\sqrt{704.54} =26.54 \,m/s^2[/tex]
Learn more about circular motion here:
https://brainly.com/question/2562955
What is the average speed of a dancer who moves 4 meters across the stage in 16 seconds?
Answer:
[tex]v=0.25 \frac{m}{s}[/tex]
Explanation:
Hello,
In this case, since the average velocity is computed as the change in the distance divided by the elapsed time:
[tex]v=\frac{\Delta x}{\Delta t}[/tex]
As 4 m were displaced in 16 seconds, the average speed turns out:
[tex]v=\frac{4m}{16s} \\\\v=0.25 \frac{m}{s}[/tex]
Best regards.
Forces of 11.9 N north, 19.1 N east, and 14.4 N south are simultaneously applied to a 3.77 kg mass as it rests on a frictionless air table. What is the magnitude of its acceleration?
There are two containers of equal volumes, each filled with a different gas. Both containers have the same number of moles of gas and are at the same temperature. The molecules of gas in container 1 are four times more massive than the molecules of gas in container 2. The number of moles in container 2 is increased until it is a factor of 4 larger than the number of moles in container
1. The volume and temperature of container 2 remain unchanged. After increasing the number of moles in container
2: Which container, 1 or 2, has a higher pressure, or are they the same? Which container, 1 or 2, has a higher average (rms) speed of gas molecules, or are they the same? Which container, 1 or 2, has a higher average kinetic energy of gas molecules, or are they the same? Which container, 1 or 2, has a higher thermal energy, or are they the same?
Answer:
Molecules in container 2 has a higher pressure.
Molecules in container 2 has a greater rms speed.
Molecules in container 2 has a greater kinetic energy.
Molecules in container 2 has a greater thermal energy.
Explanation:
At constant volume and temperature, The number of moles of a gas is proportional to its pressure.
The lower the pressure, the lesser the rms speed of molecules, kinetic energy of the molecules and thermal energy of the molecules, hence the answer above.
Q3. What is the symbol for a :-
(a) millimeter
(b) micrometer
(c) centimeter
(d) kilometer
(e) metre
(f) nanometer
Explanation:
a. mm
b. μm
c. cm
d. km
e. m
f. nm
16. A kettle used at a building site is filled with 25 liters of water at 16 °C. The water is heated until it reaches 90 °C. Calculate the amount of heat required in kJ.
Answer:
The Heat is [tex]Q = 7736.7 \ KJ[/tex]
Explanation:
Generally from the question we are told that
The volume of the water is [tex]V = 25 L = \frac{25}{1000} = 0.025 \ m^3[/tex]
The initial temperature is [tex]T_i = 16^oC = 16 + 273 = 289 \ K[/tex]
The final temperature is [tex]T_f = 90^o C = 90 + 273 = 363 \ K[/tex]
Generally the heat required is mathematically represented as
[tex]Q = m * c_w * (T_f - T_i)[/tex]
Here [tex]c_w[/tex] is the specific heat capacity of water with value [tex]c_w = 4182 J/(K kg)[/tex]
m is the mass of the water which is mathematically represented as
[tex]m = \rho * V[/tex]
Here [tex]\rho[/tex] is the density of the water which has a value [tex]\rho = 1000 kg/m^3[/tex]
So
[tex]m = 0.025 * 1000 = 25 kg[/tex]
So
[tex]Q = 25 * 4182 * (363 - 289)[/tex]
=> [tex]Q = 7736700 \ J[/tex]
Converting to KJ
[tex]Q = \frac{ 7736700}{1000}[/tex]
=> [tex]Q = 7736.7 \ KJ[/tex]
A car in a roller coaster moves along a track that consists of a sequence of ups and downs. Let the
x axis be parallel to the ground and +y axis point upward. In the time interval from t=0 to t=4 s the trajectory of the caralong a certain section of the track is given by
→r=A(1 m/s)t^i+A((1 m/s3)t3−6(1 m/s2)t2)^j, where A is positive dimensionless constant.a. At t=2.0s is the roller coaster car ascending or descending?
b. Derive a general expression for the speed v of the car. Make sure that your expression would give the correct value for the speed (in m/s), but you don't need to put in anything explicitly about units (unlike what you see in the original expressionfor →r. Express your answer in meters per second in terms of A and t.
Answer:
Explanation:
r=A(1 m/s)t^i+A((1 m/s3)t3−6(1 m/s2)t2)^j,
dr / dt = A i + (3 A t² - 6 x 2 t ) j
At t = 2
dr / dt = A i + (12A - 24 A ) j = A i - 12 A j .
Since slope is negative so velocity is downwards , hence it is descending
b ) velocity = dr / dr = . A i + (3 A t² - 6 x 2 t ) j
Vx = A
Vy = 3A t² - 12 t
A car is coasting to a stop with a constant acceleration. The car was going 35 m/s when the driver started coasting. The car moves 50. m forward while slowing down.
Show this on a vt graph.
Determine the acceleration of the car.
Answer: Plot each graph on the same coordinate system.
35 ( m/ s)
50 m
a v t.
Answer:
I think the car is accelerating at 85 m/s because the car is moving at 35/m plus when it was coasting it went 50.
Explanation:
Sorry I dont have a graph but here is what I think about on the acceleration.
Calculate the distance moved by a runner who runs with a speed of 5 km/h for a period of 1.5 hours.
7.5 km
10 km
2.5 km
5 km
Answer:
7.5 km
Explanation:
h5 per hour means that he traveled 5 km in 1 our. And then half of the hour, which means half an hour 5 km which is 2.5.
5 + 2.5 = 7.5
or just 1.5 x 5 = 7.5
A .What is the difference between fossils fuels and nuclear fuel ?
B .Explain why it is important for us to find alternatives to fossil fuels to meet pur energy?
C .What are renewable energy sources?give three examples.
Answer:
A. Nuclear and fossil fuel-burning power plants differ mainly in where their energy comes from; a nuclear reactor produces heat from radioactive metals, and a fossil-fuel plant burns coal, oil or natural gas.
B. Environmental and economic benefits of using renewable energy include: Generating energy that produces no greenhouse gas emissions from fossil fuels and reduces some types of air pollution. Diversifying energy supply and reducing dependence on imported fuels
C. These are energy sources that are constantly being replenished, such as sunlight, wind, and water.
The most popular renewable energy sources currently are:
Solar energy.
Wind energy.
Hydro energy.
Tidal energy.
Geothermal energy.
Biomass energy.
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plz if you want mark my answer as brainlesst
noise pollution may cause partial hearing impairment true or false
Answer: True
Explanation: When people pollute it breaks down the earth, that is why icebergs are melting and animals are going extinct. Before we know it, people are gonna start losing hearing, and there brain will shut down. That is also why people should stop polluting.
2. A fish swimming at a constant speed of 18 m/s spots a sta-
tionary barracuda. Just as the fish passes the barracuda, the
predator begins swimming with a constant acceleration of
magnitude 2.2 m/s². The fish and barracuda are moving in the
same direction.
(a) How far does the barracuda swim before catching the fish?
(b) At what time will this occur? (Hint: Graphing may help you
visualize this problem.)
пип
Answer:
a) 294.55 meters
b) 16.4 seconds
Explanation:
The suggested graph shows ...
(a) The barracuda swims 294.55 meters before the it catches the fish.
__
(b) This occurs after about 16.4 seconds.
Which question cannot be answered through making measurements?
A. How much carbon dioxide is released into the atmosphere when a
square mile of tropical rain forest burns?
B. Should the government invest in technologies that can reduce the
rate of global warming?
C. Which human activities contribute to global warming?
D. What is the relationship between carbon dioxide emissions and
average global temperature?
Answer: it would be A
Explanation: how are we to measure the air of a square mile
Answer: Should the government invest in technologies that can reduce the
rate of global warming?
Explanation: Trust me
Let A be the last two digits, and let B be the last three digits, and the C be the sum of the last 4 digits of your 8-digit student ID. (Example: For 20245347, A = 47, B = 347, and C = 19) A train moves at an average speed of (23.0 + A) m/s for (250.0 + B) seconds and then at an average speed of (45.0 + C) m/s for (800.0 + B) seconds. Determine the average speed for the entire time in meters per second (m/s). Round your final answer to 3 significant figures.
Answer:
66.053m/s
Explanation:
A = 47
B = 347
C = 19
Train moves at
(23 + A)m/s
= 23 + 47 = 60m/s
At (250.0+B) seconds
250.0+347 =
547 seconds
Distance d,
= 70 x 597
= 41790
It also moves at
(45.0 + c)
= 45 + 19
= 64m/s
Time = 800 + B
= 800 + 347
= 1147
Distance,
= 64 x 1147
= 73408m
Total distance,
= 73408 + 41790
= 115,198
Total time,
= 597 + 1147
= 1744
Average speed,
= Total distance / total time
= 115198/1174
= 66.053m/s
If a person and wheelchair have a combined weight of 185 lb, how much ideal effort
force is required to travel up the ramp?
Answer:
Effort force[tex]=824.04 \sin\theta[/tex]
where [tex]\theta[/tex] is the angle of inclination of the ramp.
Explanation:
The given combined mass of a person and wheelchair is 185 lb.
In SI unit, 1 pound= 0.453592 kg
So, 185 lb=[tex]185\times0.453592[/tex] kg=84kg (approximately)
Assuming the whole mass as a point mass and denote it by M, so
M=84kg
Let the angle of inclination of the ram with the is [tex]\theta[/tex] with respect to the ground and assume that the friction offered by ram id negligible, so neglection the frictional force.
The applied effort force, F, will be minimum when applied in the direction parallel to the ramp surface as shown in the figure.
The gravitational force action on M is Mg in the downward direction.
For the mass M to be at an equilibrium condition on the ramp, the sum of the total force in any direction will be zero.
Equate the sum of all the forces in the direction parallel to the ramp to zero.
[tex]F-Mg\sin\theta=0[/tex]
[tex]\Rightarrow F=Mg \sin\theta[/tex]
[tex]\Rightarrow F=84\times 9.81\sin\theta[/tex]
[tex]\Rightarrow F=824.04\sin\theta N[/tex].
When a ball is thrown straight up with no air Resistance, the acceleration is in what direction ?
Answer:
The ball has a velocity upwards but the acceleration is downwards. Gravity is giving the ball a downwards acceleration from the moment the ball leaves the hands.
A car is traveling north with a velocity of 18.1 m/s. Find the velocity of the car after 7.50 seconds if the acceleration is 2.4 m/s^2. *
Using a set of observations to test a hypothesis.
Sandra shot a rocket so that it moved with an initial velocity of 9.81 m/s straight upward. The rocket leaves and returns to ground level. What is the total time the rocket was in the air before it strikes the ground? (Ignore air resistance.
Answer:
2.00 seconds.
Explanation:
The following data were obtained from the question:
Initial velocity (u) = 9.81 m/s
Total time in air (T) =..?
Next, we shall determine the time taken for the rocket to reach it's maximum height. This can be obtained as follow:
Note: At maximum height, the final velocity is zero.
Initial velocity (u) = 9.81 m/s
Final velocity (v) = 0 m/s
Acceleration due to gravity (g) = 9.8 m/s²
Time to reach the maximum height (t) =.?
v = u – gt (since the rocket is going against gravity)
0 = 9.81 – 9.8t
Rearrange
9.8t = 9.81
Divide both side by 9.8
t = 9.81/9.8
t = 1.00 s
Therefore the time taken to reach the maximum height is 1.00 second.
Finally, we shall determine the total time spent by the rocket in the air as follow:
Time to reach the maximum height (t) = 1.00 s
Total time in air (T) =..?
T = 2t
T = 2 × 1.00
T = 2.00 s
Therefore, the total time spent by the rocket in the air is 2.00 seconds.
Which of these is only a physical change?
A. Melting a solid
B. Burning
C. Rusting
D. Forming a precipitate
A 25.0 kg bag of peat moss sits in the back of a flatbed truck, driving up a hill. The bag experiences a 225N normal force. The maximum acceleration the truck can have so the bag does not slip is 2.40 m/s2 . Calculate the (a) angle of the hill relative to horizontal and (b) coefficient of static friction between the bag and the truck. (c) The truck is now travelling on level ground at constant speed. The sand bag is tossed forward sliding along the truck bed with a horizontal speed of 2.55 m/s. If the coefficient of kinetic friction is 0.350, how far does the bag slide before coming to rest
Answer:
a
[tex]\theta = 23.32^o [/tex]
b
[tex] \mu_s = 0.27 [/tex]
c
[tex] s = 0.948 \ m [/tex]
Explanation:
From the question we are told that
The mass of the bag is [tex]m_b = 25.0 \ kg[/tex]
The normal force experienced is [tex]F_n = 225 \ N[/tex]
The maximum acceleration of the bag is [tex]a = 2.40 \ m/s^2[/tex]
Generally this normal force experience by the bag is mathematically represented as
[tex]F_n = mg cos \theta[/tex]
=> [tex]225 = (25 * 9.8) cos \theta[/tex]
=> [tex] 0.9183 = cos \theta[/tex]
=> [tex]\theta = cos^{-1}[0.9183][/tex]
=> [tex]\theta = 23.32^o [/tex]
Generally for the bag not to slip , it means that the frictional force is equal to the sliding force
[tex]F_f = F_s[/tex]
Hence [tex]F_f [/tex] is mathematically represented as
[tex]F_f = \mu_s * F_n [/tex]
While [tex]F_s [/tex] is mathematically represented as
[tex]F_s = m * a [/tex]
So
[tex] \mu_s * F_n = m * a [/tex]
=> [tex] \mu_s * 225 = 25 * 2.40 [/tex]
=> [tex] \mu_s = 0.27 [/tex]
Generally from the workdone equation we have that
[tex]KE_f - KE_i = W_f[/tex]
Here [tex]W_f[/tex] is the work done by friction which is mathematically represented as
[tex]W_f = m * g * \mu_k * s[/tex]
Here s is the distance covered by the bag
[tex]KE_f[/tex] is zero given that velocity at rest is zero
and
[tex]KE_i = \frac{1}{2} * m* v_i^2[/tex]
so
[tex] \frac{1}{2} * m* v_i^2 = m * g * \mu_k * s [/tex]
=> [tex] \frac{1}{2} * v_i^2 = g * \mu_k * s [/tex]
substituting 2.55 m/s for v_i and 0.350 for \mu_k we have that
[tex] \frac{1}{2} * 2.55^2 = 9.8 * 0.350 * s [/tex]
=> [tex] s = 0.948 \ m [/tex]
The items in a mixture can be returned to their original form.
True
False
Answer:
I believe it is true
If not, pls let me know. :)
2. The visible region of the hydrogen spectrum results from relaxation of electrons from excited states to energy level 2 (n1). Use the Rydberg equation and your measured wavelengths to determine the energy transitions associated with each of your observed wavelengths for hydrogen. In other words, calculate the excited state energy level (n2) for each of your observed wavelengths for hydrogen. n has integer values; so, calculate it first with appropriate significant digits, then round it to an integer. Use the key to show your work for at least one calculation. Must show energy levels for each hydrogen wavelength.
Answer:
E = 1.89 eV , E = 2.56 eV , E = 2.86 eV
Explanation:
The emission of light in the visible range, explained by the Balmer series with expression
1 /λ= [tex]R_{H}[/tex] (1/2² - 1 / n²)
n = 3, 4, 5 ...
the constant R_{H} called Rydberg's constant and is equal to 1,097 10⁷ m⁻¹
These transitions are clearly explained by Bohr's atomic model, where the empirical series of Balmer and Rydberg are deduced from a theoretical model of the hydrogen atom in natural form.
Let's calculate the wavelengths for each transition
State
initial final λ (10⁻⁷ m)
3 2 6.5634
4 2 4.8617
5 2 4.3408
Let's calculate the energy of each of these wavelengths using Planck's equation
E = h f = h c /λ
λ = 6.5634 10⁻⁷ m
E = 6.63 10⁻³⁴ 3 10⁸ / 6.5634 10⁻⁷
E = 3.03 10⁻¹⁹ J
we reduce to eV
E = 3.03 10⁻¹⁹ J (1 eV / 1.6 10⁻¹⁹ J)
E = 1.89 eV
λ = 4.8617 10⁻⁷m
E = 6.63 10⁻³⁴ 3 10⁸ / 4.8617 10⁻⁷
E = 4.09 10⁻¹⁹ J
E = 2.56 eV
λ= 4.3408 10⁻⁷ m
E = 6.63 10⁻³⁴ 3 10⁸ / 4.3408 10⁻⁷
E = 4.582 10⁻¹⁹J
E = 2.86 eV
What is the acceleration at the apex of a vertical up and down problem?
Answer:
The correct option is +9.81 m/s²
Explanation:
The acceleration of a vertical (up and down) plane depends on if the object is going up or down. Acceleration due to gravity is 9.81 m/s/s or 9.81 m/s². When an object falls/comes down (vertically) without interference, the acceleration of such an object is same as acceleration due to gravity (+9.81 m/s²). However, when an object is thrown/goes up, the acceleration of such objects goes against the gravity (of earth) hence the acceleration is -9.81 m/s².
At the top/apex of a vertical up and down problem, the object will be pulled back down (because of gravity) and hence, it's acceleration becomes +9.81 m/s² (changing from negative while coming up to positive).
A truck heading east has an initial velocity of 6/ms. It accelerates at 2/ms2 for 12 seconds. What distance does the truck travel in the given time
Answer:
216m
Explanation:
As we know S=ut+1/2at^2
S=6×12+1/2×2×12×12
=72+144
=216 m
Help please it’s due by 11:59p
Answer: 6 m/s squared
Explanation:
6m/s squared. Hope this helped
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