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dolphi86 [110]
2 years ago
14

Danielle is doing some DIY. She uses a 1.2kW electric saw for 20 minutes and then a 1000W electric sander for half an hour. Whic

h job is the more expensive in terms of electricity used - sawing or sanding?
Physics
1 answer:
mixas84 [53]2 years ago
4 0

Answer:

1.2kw because it is kilowatt

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A 20 watt lightbulb uses 20 Joules of energy every second.A person expends 50 watts of energy per stair when climbing up stairs.
Pachacha [2.7K]
20W = 20 J/s

Energy expended during climbing stairs = 50 W of energy/stair = 50J/stair

For 20 stairs, Total energy = 50x20 = 1000 J

This can light bulbs for, T= 1000J/20 J/s =50 seconds
6 0
2 years ago
Which statement about electrons and atomic orbitals is NOT true?
balandron [24]

<em>An electron has the same amount of energy in all orbitals  is not true</em>

\boxed{\boxed{\bold{Further~explanation}}}

In an atom there are levels of energy in the skin and sub skin.

  • This energy level is expressed in the form of electron configurations.

Writing electron configurations starts from the lowest to the highest sub-shell energy level.

So electrons that occupy the orbitals in the lowest sub-skin have the lowest energy level

  • In the principle of Pauli's prohibition it was stated that there are no two electrons in one atom that can have the same four quantum numbers.

So suppose that there are two electrons occupying one orbital can have the same main quantum number (n), azimuth (l) and magnetic (m), then the last quantum number that is the quantum spin number (s) must be different.

So that the two electrons are different from just the quantum spin number, even though the other quantum numbers are the same.

So in one orbital only a maximum of 2 electrons is occupied, because if there is a third electron, this third electron will have the same quantum spin number as the previous electron

  • The electron cloud is a visual representation of the location of electrons in an atom.

Orbital is the place around the nucleus where electrons may be found

Electron clouds show the state of electrons in their orbitals

So electron clouds can show the condition of all orbitals in an atom

The lowest energy level of an electron occupies a sub-skin of 1s which has only one orbital

Charging electrons in the sub skin uses the following sequence:

1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁶, 5s², 4d¹⁰, 5p⁶, 6s², etc.

Statement about electrons and atomic orbitals is not true is An electron has the same amount of energy in all orbitals

the electron configuration for barium (Ba) in noble-gas notation brainly.com/question/11147367

the formation of a bond.

brainly.com/question/11311275

quantum number

brainly.com/question/2292596

Keywords: the electron configuration, orbitals, atoms, energy, skin, sub skin, electron clouds

8 0
2 years ago
Read 2 more answers
A pitcher throws a 0.15 kg baseball so that it crosses home plate horizontally with a speed of 10 m/s. It is hit straight back a
Maru [420]

Answer:

-5.1 kg m/s

Explanation:

Impulse is the change in momentum.

Change in momentum= final momentum - initial momentum=mv_{2} +mv_{1}

Plugging in the values= -0.15*24 - (0.15*10) (The motion towards the pitcher is negative as the initial motion is considered to be positive)

Impulse=-5.1 kg m/s (-ve means that it is the impulse towards the pitcher)

4 0
2 years ago
A person is standing outdoors in the shade where the temperature is 35 °C.
Free_Kalibri [48]

Answer:

(a) Eₐ = 6.36 J/s

(b) Eₐ = 4.64 J/s

Explanation:

Stefan-Boltzmann law: States that the total energy per second radiated or absorbed by a black body is directly proportional to the absolute temperature.

Using, Stefan-Boltzmann equation

Eₐ =eσAT⁴ ................ Equation 1

where Eₐ = Radiant energy absorbed per seconds, e = emissivity, σ = stefan - boltzman constant, A = Surface area. and T = temperature in kelvin

(a) Where e = 0.89, σ = 5.67 ×10⁻⁸ watt/m²/K⁴, A = 140 cm² = 140 cm²(m²/10000cm²) = 0.014 m², T = 35 °C = (35 + 273) K = 308 K.

Applying these values in equation 1 above,

Eₐ = 0.89 × 5.67 ×10⁻⁸ × 0.014 × (308)⁴

Eₐ =6.36 J/s

(b) when e = 0.65,

∴ Eₐ = 0.65 × 5.67 × 10⁻⁸ × 0.014 × (308)⁴

 Eₐ = 4.64 J/s

6 0
2 years ago
Water floats on a liquid called "carbon tetrachloride." The two liquids do not mix. A light ray passing from water into carbon t
Oduvanchick [21]

Answer:

1.26

Explanation:

index  \: of  \: refraction \:  =  \:  \ \frac{ \sin(angle \: of \: incidence) }{ \sin(angle \: of \: refraction) }

\frac{ \sin(45.0) }{ \sin(40.1) }

= 1.26

5 0
2 years ago
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