Answer:
the two lines observed correspond to Hydrogen and Helium
Explanation:
One of the great principles of atomic physics is that the emission and absorption lines of atoms are the same, in addition, each different element has a series of characteristic lines with which we can identify it.
Bohr's atomic model allows to fully explain the spectrum of lines and absorption of Hydrogen, in this case the line
λ = 656 nm
corresponds to a hydrogen trasition of the Balmer series from state n = 3 to state n = 2
The other line identified λ = 587 nm does not correspond to any hydrogen line and neither to heavy element lines, so this line when it was discovered was assigned to a new element, which was called Helium. This line is explained this element was assigned an atomic number (charge) of +2 and a mass of + 4 u, specifically it is a transition from level n = 3 to level n = 2
therefore the two lines observed correspond to Hydrogen and Helium
You have two electrical devices plugged into the same socket in parallel and draws 120 V. The first device has a resistance of 20 Ω the other device has a resistance of 10 Ω.
What is the total resistance?
The devices don't "draw" 120v. The 120v comes to your house from the power company. They decide it should be 120v and that's what they send you. It's hypothetically technically possible for you to change that, but if you try it, you'll definitely burn the house down.
The total resistance of those two devices in parallel is 6 and 2/3 ohms. That doesn't depend on what they're plugged into. It would still be 6 and 2/3 ohms if they were connected in parallel, wrapped in tissue, sealed in a jar of chicken soup and stored in a box on a high shelf.
But since they ARE plugged into 120v, they draw 18 Amperes from the socket, and they turn all of that electrical energy into 2160 watts of heat. That's about the same as a good size toaster oven, and you have to figure out a way to get rid of all that heat before you burn the house down.
Which of these devices is a type of aerobic exercise machine?
Answer:
Aerobic exercise is an important component of a healthy lifestyle. Find out more about aerobic equipment that can help keep you fit.
Aerobic equipment simulates the movements of aerobic exercises such as walking, jogging, rowing, skiing, hiking, biking, and climbing. These activities rhythmically and continuously move your large muscles — the key to getting your heart beating fast enough and long enough for aerobic conditioning.
The bands on Jupiter are ultimately caused by...
the Coriolis effect.
its magnetic fields.
precession.
the Great Red Spot.
Aluminum has an alpha value of 25 x 10^-6 1/degrees C. What is the change in
length of a 4850 cm wire at 2 degrees C when the temp increase to 55 degrees
C?
Answer:
6.4 cm.
Explanation:
From the question given above, the following data were obtained:
Coefficient of linear expansion (α) = 25×10¯⁶ / °C
Original length (L) = 4850 cm
Initial temperature (T₁) = 2 °C
Final temperature (T₂) = 55 °C
Change in length (ΔL) =?
The change in the length of the wire can be obtained as follow:
α = ΔL / L(T₂ – T₁)
25×10¯⁶ = ΔL / 4850(55 – 2)
25×10¯⁶ = ΔL / 4850 × 53
25×10¯⁶ = ΔL / 257050
Cross multiply
ΔL = 25×10¯⁶ × 257050
ΔL = 6.4 cm
Therefore, the change in the length of the wire is 6.4 cm
20/05/2021
BP102T
- Which one of the following statements about reaction rate is false?
3253505030
Reaction rates are not sensitive to temperature.
Reaction rate is governed by the energy barrier between reactants and products.
Reaction rate is the speed at which the reaction proceeds.
Enzymes can accelerate the rate of a reaction.
Answer:
Reaction rate are not sensitive to temperature.
An 80 kg astronaut has gone outside his space capsule to do some repair work. Unfortunately, he forgot to lock his safety tether in place, and he has drifted 5.0 m away from the capsule. Fortunately, he has a 1000 W portable laser with fresh batteries that will operate it for 1.0 h. His only chance is to accelerate himself toward the space capsule by firing the laser in the opposite direction. He has a 10-h supply of oxygen. His only chance is to accelerate himself toward the space capsule by firing the laser in the opposite direction. He has a 10-h supply of oxygen.
Required:
How long will it take him to reach safety?
Answer:
t = 3.924 s
Explanation:
First, we will calculate the amount of work required to get the astronaut back to the capsule:
[tex]W = Fd\\[/tex]
where,
W = work required = ?
F = Force = Weight = mg = (80 kg)(9.81\ m/s²) = 784.8 N
d = distance = 5 m
Therefore,
[tex]W = (784.8\ N)(5\ m)\\W = 3924 J[/tex]
Now the time can be calculated as:
[tex]Power = \frac{W}{t}\\t = \frac{W}{Power}\\\\t = \frac{3924\ J}{1000\ W}\\\\[/tex]
t = 3.924 s
Plz help The momentum of a baseball changes dramatically when struck by a bat.Momentum of the ball is not conserved. The best explanation for this is that
Answer:
The answer is C the ball is not in a closed system and experience an impulse.
Explanation:
After landing on an unfamiliar planet, a space explorer constructs a simple pendulum of length 48.0 cm . The explorer finds that the pendulum completes 93.0 full swing cycles in a time of 141 s.
Required:
What is the value of g on this planet?
Answer:
8.24 m/s²
Explanation:
Applying,
T = 2π√(L/g).................... Equation 1
Where T = period of the pendulum, L = Length of the pendulum, g = acceleration due to gravity of the planet, π = pi
From the question, we were asked to find the value of g,
There we make g the subject of the equation
g = 4π²L/T²..................... Equation 2
Given: L= 48 cm = 0.48 m, T = (141/93) s = 1.516 s
Constant: π = 3.14
Substitute these values into equation 2
g = 4(3.14²)(0.48)/(1.516²)
g = 18.93/2.298
g = 8.24 m/s².
Hence the acceleration of the planet is 8.24 m/s²
How are radar and an approaching siren alike? How are they different?
A. Both use sound waves, but the Doppler effect can be observed
only with radar.
B. Both use sound waves, but the Doppler effect can be observed
only in the approaching siren.
C. Both exhibit the Doppler effect, but radar uses radio, and the siren
'uses sound waves.
D. Both exhibit the Doppler effect, but radar uses sound waves, and
the siren uses radio.
Answer: D
Explanation: I just took the test
Answer: Both exhibit the Doppler effect, but radar uses radio, and the siren' uses sound waves.
Explanation: I took the test
A convex lens has a focal length of 0.33 m. The object distance is 0.7 m. What is the image distance?
Answer:
Explanation:
1/v - 1/u = 1/f
given, f = 0.3 m, u = -0.4m
so, 1/v - 1/-0.4 = 1/0.3
or, 1/v = 1/0.3 - 1/0.4 = 1/1.2
v = 1.2 m
now, differentiating 1/v - 1/u = 1/f with respect to t,
-1/v² dv/dt + 1/u² du/dt = 0
or, dv/dt = (v/u)² du/dt
putting, du/dt = 0.01 m/s , v = 1.2 m and u = -0.4 m
so, dv/dt = (1.2/-0.4)² × 0.01
= 0.09 m/s
hence, speed of image with respect to lens is 0.09 m/s .
from formula of magnification
magnification, m = v/u
differentiating with respect to time both sides,
dm/dt = (u dv/dt - vdu/dt)/u²
= (-0.4 × 0.09 - 1.2 × 0.01)/(-0.4)²
= (-0.036 - 0.012)/0.16
= -0.048/0.16
= -0.3 m/s
hence, magnitude of rate of change of lateral magnification is 0.3 m/s
Claire pushes a box to the left while Jamie pushes the same box to the right. The box stays in
between them in the same position.
Which best explains why Claire and Jamie are unable to move the box?
A. They are applying an unbalanced force.
B. They are applying a balanced force.
C. They are applying gravity.
D. They are applying friction.
what is made by placing a piece of iron inside a coil of wire carrying a current
Answer:
electromagnet
Explanation:
Magnet
.....
In the chapter on psychoactive drugs within this week's module, a table shows various
psychoactive drugs and the neurotransmitters that those drugs effect. Which of the following
neurotransmitters is effected by marijuana?
Serotonin
Blood
Acetylcholine
GABA
Answer:
marijuana effects on Serotonin and GABA
Explanation:
A psychoactive drug is a chemical that changes our states of consciousness, and particularly our perceptions and moods. These drugs are commonly found in everyday foods and beverages, including chocolate, coffee, and soft drinks, as well as in alcohol and in over-the-counter drugs, such as aspirin, Tylenol, and cold and cough medication. Psychoactive drugs are also frequently prescribed as sleeping pills, tranquilizers, and antianxiety medications
These drugs are thought to raise serotonin levels by inhibiting the reuptake process that brain cells use to remove excess serotonin. But several lines of evidence suggest that marijuana has negative effects on serotonin levels and may block the action of serotonin-boosting
The drug activates CB1 receptors on GABAergic and glutamatergic neurons in the ventral tegmental area (VTA), inhibiting the activity of both. CB1 inhibition of GABA neurons promotes, and inhibition of glutamate dampens, VTA dopaminergic neurons' activity and dopamine release in the NAC.
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Question 3 of 5 What happens to the particles in a substance as it melts? O A. The particles slow down and become fixed in place. B. The particles move more quickly but stay fixed in place. O C. The particles slow down and move closer together, but they can still move around. O D. The particles move more quickly and begin to move from place to place. SUBMIT
Answer:
D. The particles move more quickly and begin to move from place to place.
Explanation:
26. Acceleration Tecle, with a mass of 65.0 kg, is
standing on an ice-skating rink. His friend
applies a force of 9.0 N to him. What is Tecle's
resulting acceleration?
Force = mass × acceleration
9 = 65 x acceleration
acceleration= 9/65 = 0.318 m/s2
Acceleration Tecle, with a mass of 65.0 kg, is standing on an ice-skating rink. His friend applies a force of 9.0 N to him. Tecle's resulting acceleration is 0.318 m/s²
What is acceleration?The rate at which an item changes its velocity is known as acceleration, a vector quantity. If an object's velocity is changing, it is acceleration.
The net acceleration that objects get as a result of the combined action of gravity and centrifugal force is known as the Earth's gravity, or g. It is a vector quantity whose strength or magnitude is determined by the norm and whose direction correlates with a plumb bob.
Force = mass × acceleration
9 = 65 x acceleration
acceleration= 9/65 = 0.318 m/s²
Acceleration Tecle, with a mass of 65.0 kg, is standing on an ice-skating rink. His friend applies a force of 9.0 N to him. Tecle's resulting acceleration is 0.318 m/s²
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Explain what you understand by Millennial Generation
Answer:
refers to the generation of people born between the early 1980s and 1990s
If the frequency of a wave is doubled, what happens to that waves energy
Answer:
If the frequency of a wave is doubled, what happens to its wavelength? If the frequency is doubled, the wavelength is only half as long. 3. ... As the frequency slows down, the wavelength increases.
Explanation:
A bolt of lightning discharges 9.7 C in 8.9 x 10^-5 s. What is the average current during the discharge?
Answer: [tex]1.089\times 10^5\ A[/tex]
Explanation:
Given
Charge discharged [tex]Q=9.7\C[/tex]
time taken [tex]t=8.9\times 10^{-5}\ s[/tex]
Current is given as rate of change of discharge i.e.
[tex]\Rightarrow I=\dfrac{Q}{t}\\\\\Rightarrow I=\dfrac{9.7}{8.9\times 10^{-5}}\\\\\Rightarrow I=1.089\times 10^5\ A[/tex]
Therefore, the average current is [tex]1.089\times 10^5\ A[/tex]
a student standing in an elevator at rest notices that her pendulum has a frequency of oscillation of 0.5 Hz. a. what is the length of the pendulum's string? b. the elevator starts to accelerate upwards. what effect will this have on the oscillation? explain.
Explanation:
Given that,
The frequency of oscillation, f = 0.5 Hz
(a) Let the length of the pendulum string is l. So,
[tex]T=2\pi \sqrt{\dfrac{l}{g}}[/tex]
T is time period, T = 1/f
So,
[tex]l=\dfrac{(\dfrac{1}{f})^2g}{4\pi ^2}\\\\l=\dfrac{(\dfrac{1}{0.5})^2\times 9.8}{4\times 3.14 ^2}\\\\l=0.993\ m[/tex]
(b) When the elevator starts to accelerate upwards, new acceleration is a+g. If accelerating upward, the value of g has increased, because of inertia. So it will feel heavier and the period will decrease.
You drop a 10 kg bowling ball off a 2 story building, what is the force generated by
the bowling ball when it hits the ground
Answer:i
Explanation:
Select the correct answer from each drop-down menu.
After World War II, political leaders from various countries discussed ways to strengthen individual-as well as
economies. They began promoting
to boost production and exports,
Answer: I think it’s Global for the 1st one
And free trade for the 2nd one
Explanation:
The correct answer is: "After World War II, political leaders from various countries discussed ways to strengthen individual economies." They began promoting economic policies to boost production and exports.
What happened after World War II?After World War II, many countries were left with weakened economies and infrastructure, and there was a need for economic recovery and growth. To achieve this, political leaders from different countries came together to discuss ways to strengthen their individual economies and also promote international economic cooperation. One of the ways they did this was by promoting economic policies that aimed to boost production and exports. This involved policies that encouraged businesses to increase their output and create more jobs, as well as policies that made it easier for countries to trade with each other.
Hence, after World War II, political leaders from various countries discussed ways to strengthen their individual economies. They began promoting economic policies to boost production and exports.
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a 4 kg block is moving at 12 m/s on a horizontal frictionless surface. a constant force is applied such that the block slows with an acceleration of 3 m/s^2. how much work must this force do to stop the block?
a. -576 J
b. -360 J
c. -288 J
d. 360 J
e. 576 J
Answer:
c. -288 J
Explanation:
Given;
mass of the block, m = 4 kg
velocity of the block, v = 12 m/s
deceleration of the block, a = 3 m/s²
Apply work-energy theorem;
work done in stopping the block = kinetic energy of the block
W = ¹/₂mv²
where;
W is the magnitude of the work done by the force
W = ¹/₂ x 4 x 12²
W = 288 J
Since the work done by the force is in opposite direction, then the value of the work done by the force is -288 J
An open cart is rolling to the left on a horizontal surface. A package slides down a chute and lands in the cart. Which quantity or quantities have the same value just before and just after the package lands in the cart
Answer: the horizontal component of total momentum
Explanation:
Since the open cart is rolling to the left on the horizontal surface, the quantity that has the same value just before and just after the package lands in the cart is the horizontal component of total momentum.
Momentum, is the product of the mass of a particle and the velocity of the particle. The change of momentum depends on the force which acts on it. The addition of the the individual momenta is the total momentum.
If 03.4 kg of water at 69°C is changed into steam at 100°C, how will the energy be used? specific heat capacity of water is 4200J/kg C and latent heat is 2,260 000J/Kg.
A. 7864513 J
B. 8126680 J
C. 329758 J
D. 742976 J
With explanation please
Answer:
The answer is B.
Explanation:
مافيني اشرح
how much thermal energy is created when a 3000 kg suv brakes to a stop from 20 m/s on a level road?
a. 1,200,000 J
b. 600,000 J
c. 60,000 J
d. 30,000 J
e. 90,000,000 J
Answer:
b. 600,000 J
Explanation:
Applying the law of conservation of energy,
The thermal energy created = Kinetic energy of the suv.
Q' = 1/2(mv²)............... Equation 1
Where Q' = Thermal energy, m = mass of the suv, v = velocity of the suv.
From the question,
Given: m = 3000 kg, v = 20 m/s
Substitute these values into equation 1
Q' = 1/2(3000×20²)
Q' = 600000 J
Hence the right option is b. 600,000 J
Phobos's Orbit. Phobos orbits Mars at a distance of 9,380 km from the center of the planet and has a period of 0.3189 days. Assume that Phobos's orbit is circular. Calculate the mass of Mars. Express your answer in units of kg. (Hint: Use the circular orbit velocity formula ; remember to use units of meters, kilograms, and seconds.) Please round the answer to four significant digits. m
Answer:
Explanation:
The relation between time period of moon in the orbit around a planet can be given by the following relation .
T² = 4 π² R³ / GM
G is gravitational constant , M is mass of the planet , R is radius of the orbit and T is time period of the moon .
Substituting the values in the equation
(.3189 x 24 x 60 x 60 s)² = 4 x 3.14² x ( 9380 x 10³)³ / (6.67 x 10⁻¹¹ x M)
759.167 x 10⁶ = 8.25 x 10²⁰ x 39.43 / (6.67 x 10⁻¹¹ x M )
M = .06424 x 10²⁵
= 6.4 x 10²³ kg .
Phase portraits (or phase diagrams) provide a powerful tool to visualize the dynamics of ODE systems.
a. True
b. False
which choice displays the effects of quantum mechanics? check all that apply
atoms
subatomic particles
particles that are 10^-9m
microtechnology systems
protons
neutrons
particles that are 10^-3m
Answer:
A,B,C,D,F,G
Explanation:
Edge 2021
The atoms, subatomic particles, particles that are 10^-9m, microtechnology systems, neutrons and particles that are 10^-3m will displays the effects of quantum mechanics.
What is Quantum Mechanics?Quantum Mechanics is the branch of mechanics deals with the mathematical description of the motion and interaction of subatomic particles, incorporating the concepts of quantization of energy, wave–particle duality, the uncertainty principle, and the correspondence principle is Quantum Mechanics.
It is theory says at subatomic level, energy exists in discrete levels as "quanta" and particles behave as waves.
A Subatomic particles are the particle that are present inside an atom. These particles are electrons, protons, and neutrons.
Thus, atoms, subatomic particles, particles that are 10^-9m, microtechnology systems, neutrons and particles that are 10^-3m will displays the effects of quantum mechanics.
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how many moles in 3.4x10^24 atoms calcium chloride
A 4500-kg helicopter accelerates upward at 2.0m/s2 what lift force is exerted by the air on the
helicopter?
Answer:
9000
Explanation:
f=ma
f= force
m=mass
a=acceleration
f=ma
4500×2.0
9000N