A 40W lamp wastes 34 J of energy every second by heating its surroundings.
What is the efficiency of the lamp?
С
18%
D
85%
A
0.15%
15%
B
Answer:
[tex]15\%[/tex].
Explanation:
The efficiency of a machine is the percentage of energy input that was turned into useful energy.
The power rating of this lamp is [tex]40\; \rm W[/tex] (same as [tex]40\; \rm J \cdot s^{-1}[/tex],) meaning that [tex]40\; \rm J[/tex] of energy is supplied to this lamp every second.
The question states that [tex]34\; \rm J[/tex] out of that [tex]40\; \rm J[/tex] of energy input would be turned into heat, which is not useful energy output in this scenario. Assuming that all other forms of energy loss is negligible. The rest of the [tex](40\; \rm J - 34\; \rm J) = 6\; \rm J[/tex] of energy supplied to this lamp would be turned into useful energy output.
Thus, every second, this lamp would receive [tex]40\; \rm J[/tex] of energy input and would outputs [tex]6\; \rm J[/tex] of useful work. The efficiency of this lamp would be:
[tex]\begin{aligned}& \text{Efficiency} \\ =\; & \frac{\text{Useful energy out}}{\text{Total energy in}} \times 100\% \\ =\; & \frac{6\; \rm J}{40\; \rm J} \times 100\%\\ =\; &15\% \end{aligned}[/tex].
How many neutrons are in K-37?
Answer:
18 neutrons
Explanation:
Potassium is nuimber 19 on periodic table, so when the mass equals 37, you simply subtract 37-19 to get 18
potassium usually has a mass of 39, so when we have potassium 37, it is two less neutrons than normal
Approximately how many kilograms (kg) of carnivore (secondary consumer) biomass can be supported by an area of a field containing 1,000 kg of plant material (assuming 10% efficiency in energy transfer)
Only 10 Kg of secondary consumers can be supported by the ecosystem.
There exists such a thing as the 10% rule in the transfer of energy in biomass from one trophic level to another. This rule ultimately controls the mass of biomass that is available at the next higher trophic level.
This rule state that only 10% of the energy in biomass is transferred to the next trophic level. By this rule, only 10% of the energy in the plant material is transferred to the carnivore population. Therefore, only 10 Kg of secondary consumers can be supported by the ecosystem.
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what 3 things make up a nucleotid
Answer:
A nucleotide consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base. The bases used in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T).
how many kilojoules is this?
Answer:
How to convert joules to kilojoules
One joule is equal to thousandth of a kilojoule:
1J = 0.001kJ
The energy in kilojoules E(kJ) is equal to the energy in joules E(J) divided by 1000:
E(kJ) = E(J) / 1000
Example
Convert 500 joules to kilojoules.
The energy E in kilojoules (kJ) is equal to 500 joules (J) divided by 1000:
E(kJ) = 500J / 1000 = 0.5kJ
Joules to kilojoules conversion table
Energy (J) Energy (kJ)
1 J 0.001 kJ
2 J 0.002 kJ
3 J 0.003 kJ
4 J 0.004 kJ
5 J 0.005 kJ
6 J 0.006 kJ
7 J 0.007 kJ
8 J 0.008 kJ
9 J 0.009 kJ
10 J 0.01 kJ
20 J 0.02 kJ
30 J 0.03 kJ
40 J 0.04 kJ
50 J 0.05 kJ
60 J 0.06 kJ
70 J 0.07 kJ
80 J 0.08 kJ
90 J 0.09 kJ
100 J 0.1 kJ
200 J 0.2 kJ
300 J 0.3 kJ
400 J 0.4 kJ
500 J 0.5 kJ
600 J 0.6 kJ
700 J 0.7 kJ
800 J 0.8 kJ
900 J 0.9 kJ
1000 J 1 kJ
2000 J 2 kJ
3000 J 3 kJ
4000 J 4 kJ
5000 J 5 kJ
6000 J 6 kJ
7000 J 7 kJ
8000 J 8 kJ
9000 J 9 kJ
10000 J 10 kJ
100000 J 100 kJ
hope it help u
itz by Riddhi
12. Since the Clean Air Act was passed in 1970, why is the air still not clean?
Answer:
Congress designed the Clean Air Act to protect public health and welfare from different types of air pollution caused by a diverse array of pollution sources.
Explanation:
If an atom has two protons and three electrons, then the atom is-?
A. positively charged.
B. negatively charged.
C. radioactive.
D. neutral.
Hope you could get an idea from here.
Doubt clarification - use comment section.
what do i do on this rubixs cube
Answer:
You solve it
Explanation:
Answer:
you just spin it and spin it and spin it and spin it
and spin it
and spin it
and spin it
and spin it
until you get mad then throw it at the wall
Explanation:
ya then you look up a vid that is called rubix cube meme and there should be a pink animal its funny you should watch it!!!!!!!!!
i. a A ball is released from a height of 45 m top of the building. If it strikes the ground surface after 5 seconds, calculate the acceleration and final velocity of the ball. [18 m/s, 3.6 m/s²].
Answer:
3.6m/s², 18m/s
Explanation:
So according to h=1/2at², 45=1/2a*25, a=3.6m/s² (which means that it didn't happen on Earth?)
Final velocity = at = 3.6*5 = 18 m/s
an EM wave has a wave length of 956 m, What type of electromagnetic waves is this wave
The electromagnetic spectrum allows finding the result for the question of type of electromagnetic wave has a wavelength of 956 nm
The wave is in the near infrared range.
The electromagnetic wave is an oscillation of electric fields and magnets field that sustain each other, this wave time has the characteristics that it can travel without a material medium, for which they are of extreme importance.
Consequently the spectrum of electromagnetic waves to each part has been given a different name second to its use, for example
Range Name
Ultraviolet light 200 to 400 nm
Visible light 400 to 700 nm
Infrared light (heat ) 700 nm to 1 mm
The latter is subdivided into:
Near infrared 700 nm to 1000 nm (1 μm)
Medium infrared 1 μm to 30 μm
Far infrared 50 μm to 1000 μm
It indicates that the wavelength of the measured radiation is 956 nm, therefore it is in the near infrared range.
Learn more about the electromagnetism spectrum here: brainly.com/question/23727978
Name the two sources of light.
Answer:
Natural light (Sun, stars.etc.) and Artificial light (Lamposts, televisions.etc.)
Hope that helps. x
What is the centripetal acceleration?
Answer:
centripetal acceleration is when an object accelerates going in a circular motion.
A medieval instrument used to determine the position of the sun:
Answer: astrolabe
Explanation:
help will give brainlist
Which unit is used for current?
power
resistance
voltage
amperes
the probe used in a medical ultrasound examination emits sound waves in air that have a wavelength of 0.12 mm.
Answer:
IF GOD IS TEIIING YOU SOMETHING JUST DO IT
Explanation:
A woman of mass 49 kg jumps off the bow
of a 78 kg canoe that is intially at rest.
If her velocity is 4.5 m/s to the right, what
is the velocity of the canoe after she jumps?
Answer in units of m/s i.
x x
The woman-canoe system has zero initial momentum. When the woman jumps from the canoe, the total momenta of the woman and canoe is conserved, so that
0 = (49 kg) (4.5 m/s) + (78 kg) v
where v is the velocity of the canoe. Solving for v, we find
(78 kg) v = - (49 kg) (4.5 m/s)
v = - 49/78 (4.5 m/s)
v ≈ -2.8 m/s
which is to say, the boat is given a velocity of 2.8 m/s to the left.
A green ball is dropped from rest from an elevated position at the same instant that a red ball is launched horizontally (from the same height), which ball will hit the ground first? Assume the balls behave as projectiles.
a. green ball
b. red ball
c. the red and green ball will hit the ground at the same time
d. not enough information given
Answer:
c. the red and green ball will hit the ground at the same time
Explanation:
if two objects are the same size but one is heavier, the heavier one has greater density than the lighter object. Therefore, when both objects are dropped from the same height and at the same time, the heavier object should hit the ground before the lighter one.
a car is travelig at 20.0 m/s when the driver applies the brakes and comes to a stop. if the car slows down uniformly with an acceleration of -4.20 m/s, about how far does the car travel before coming to a rest
Since acceleration is constant, we can use the formula
v² - u² = 2a ∆x
where v = final velocity, u = initial velocity, a = acceleration, and ∆x = displacement. Then
0² - (20.0 m/s)² = 2 (-4.20 m/s²) ∆x
⇒ ∆x = (20.0 m/s)² / (8.40 m/s²) ≈ 47.6 m
Explain why the formation of sand is a physical change.
Answer:
The formation of sand is a physical change because some of the physical properties of the rocks change, but their identities do not. The particles of rock are rearranged as their sizes and shapes change, but their identities and total mass remain the same.
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NEED THIS IMMEDIATELY TODAY
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(answer choices: applied force, normal force, friction, electrical force, magnetic force and gravitational force)
(question in picture)
Answer:
3
Explanation:
because they are pushing a body
a -0.06 C charge is placed in a uniform electric field with a strength of 200 N/C. what is the magnitude and direction of the force on the charge
The magnitude and direction of the force on the charge is -12 N opposite the electric field
To calculate the force on a charge in an electric field, we make use of the formula below.
Formula
F = E×Q .......................... Equation 1
Where:
F = Force on the chargeE = Electric FieldQ = chargeFrom the question,
Given:
E = 200 N/CQ = -0.06 CSubstitute these values into equation 1
F = 200(-0.06)F = -12 NNote: The negative sign indicates that the force is in the direction negative of the electric field.
Hence, The magnitude and direction of the force on the charge is -12 N opposite the electric field
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Answer: A edge 202694020
Explanation:
what does a pair of shoes weigh on mars?
Answer:
0.76 lbs (if shoes 2lbs)
Explanation:
Gravity on Mars is only ~38% as strong as it is on Earth, so objects would only weigh ~38% of their Earth weight.
1 point
A hairdryer uses 10 A of current when plugged into a 120 V outlet. How
much power does it use?
Answer:
1200 watt
Explanation:
P= I*V=10*120=1200watt
pls help quickly
Which of these materials best scatters the light that strikes it?
a pure water
b shiny mirror
c frosted glass
d eyeglass lens
Answer: frosted glass
Explanation:
Answer:
C
Explanation:
Frosted Glass
what is the velocity of 8.01
Answer: The velocity of what?
Marco is conducting an experiment. He knows the wave that he is working with has a wavelength of 32. 4 cm. If he measures the frequency as 3 hertz, which statement about the wave is accurate? The wave has traveled 32. 4 cm in 3 seconds. The wave has traveled 32. 4 cm in 9 seconds. The wave has traveled 97. 2 cm in 3 seconds. The wave has traveled 97. 2 cm in 1 second.
The true statement about the wave is that, the wave has traveled 97. 2 cm in 1 second.
In Physics, we define a wave as a disturbance along a medium that transfers energy. The wavelength of a wave is the distance covered by the wave while the frequency of the wave is the number of cycles of the wave completed per second.
The period of the wave is the inverse of the frequency of the wave. It is defined as the time taken for the wave to complete a cycle and it is measured in seconds.
The wave formula is given as;
v = λf
v = velocity of the wave (distance traveled by the wave in one second)
λ = wavelength of the wave
f = frequency of the wave
So;
λ = 32.4 cm
f = 3 hertz
v = 32.4 cm × 3 hertz
v = 97. 2 cms-1
Hence, the true statement about the wave is that, the wave has traveled 97. 2 cm in 1 second.
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A firecracker is placed in the middle of a room. When the firecracker explodes the parts of the firecracker scatter in all different directions. The total combined momentum of all the parts of the firecracker added together after the explosion must be
A.
more than before the explosion.
B.
less than before the explosion.
C.
can not tell from the given information
D.
the same as before the explosion.
Because momentum is a vector quantity, the total combined momentum of all the parts of the firecracker added together after the explosion must be the same as before the explosion. The correct answer is D
Given that a firecracker is placed in the middle of a room. This means that the firecracker is at rest. That is its momentum is equal to zero. When the firecracker is lit up, it will move in a certain velocity before it explodes. Since the total combined momentum of all the parts of the firecracker scatter in all different directions are considered, that is added up, then momentum will always be conserved. That is,
The momentum of an object before explosion will always be equal to the momentum of the object after explosion.
Because momentum is a vector quantity, in which we must consider it magnitude and direction, the best answer to this question is option D.
That is,
The total combined momentum of all the parts of the firecracker added together after the explosion must be the same as before the explosion
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Convert: 12 km/hr =
m/s
[tex]12~ \text{km} ~ \text{h}^{-1} = \dfrac{12 \times 1000}{3600} ~~ \text{m s}^{-1} = 3.33 ~~ \text{m s}^{-1}[/tex]
Answer:
3 1/3 or 3.3333....
Explanation:
You multiply the kilometres by 1,000 because there are 1,000 metres in a kilometre. Then you divide by 60 because there are 60 minutes per hour, and then again by 60 because 60 seconds per minute.
12,000 / 60 = 200
200 / 60 = 3.333
The practice of science can answer only scientific questions. And scientific questions guide the design of investigations. What must be true of the possible answers to a scientific question? A. They are popular with a majority of scientists. B. They agree with all prior experiments. O C. They can be supported by evidence. O D. They lead to increased funding of scientific research.
Answer:
They must be supported by evidence.
Explanation:
Every scientific theory or scientifc claim must have scientific evidence.
A 40 N block is resting on a rough inclined plane. The static friction between the block and the plane is ____ N.
The static friction between the block and the plane is [tex]40(\mu_s) \ N[/tex].
The given parameters:
Weight of the block, W = 40 NThe normal reaction on the rough surface due to weight of the block is calculated as follows;
[tex]F_n = 40 \ N[/tex]
The static friction between the block and the plane is calculated as follows;
[tex]F_s = \mu_s F_n[/tex]
where;
[tex]\mu_s[/tex] is coefficient of static frictionThus, the static friction between the block and the plane is [tex]40(\mu_s) \ N[/tex].
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