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2 years ago

In which situation is no work considered to be done by a force?

1 answer:

8 0

If the angle is either 0 or 180, that means that there is either negative or positive work, so A and D are not correct.
If the angle is 45, then there is still some work involved.
The only option where there is no work done by a force is B. when the angle is between the force and displacement is 90.

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How should parents raise their intersex children: as girls, boys or intersex?

Mice21 [21]

I believe to create a society that is without judgment, children of all sex should be raised the same.

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3 years ago

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Imagine that Earth stops orbiting the Sun but continues to rotate in place about its own axis at its current rate. In this case,

otez555 [7]

Answer:

The length of the solar day will get shorter.

Explanation:

The blue planet Earth not only rotates around it's own axis but also rotates around the Sun and everyday it moves a little bit around the axis.
Since the speed of the Earth's rotation on it's own axis and around the Sun is constant we don't feel the effects of the rotation.We can only feel the motion if the earth changes it's rotation speed.
If by any means or chance the Earth stopped spinning (stopped rotation) then the atmosphere surrounding the Earth would be in motion and all the Earth's land would be scoured clean.

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2 years ago

Wich statment belongs to Daltons atomic theroy?

lozanna [386]

Answer:

Dalton's Atomic Theory states that :-

1) All matter is made up of very tiny particles called atoms.

2) Atoms are indivisible particles , which can't be created or destroyed in a chemical reaction.

3) Atoms of a given element are identical in mass & chemical properties.

4) Atoms of very different elements have different masses & chemical properties.

5) Atoms combine in the ratio of small whole numbers to form compounds.

6) The relative number & kinds of atoms are constant in a given compound.

It's drawback's are :-

1) Atoms can be divided further into electrons , protons & neutrons.

2) According to Dalton Atomic Theory, atoms of an element are identical in mass, size and many other chemical or physical properties. But, practically we observe that atoms of several elements differ in their densities and masses. These atoms with the different masses are known as isotopes. For example, Chlorine (Cl) has 2 isotopes with the mass numbers of 35 and 37.

3) Also, according to Dalton Atomic Theory, atoms of two-different elements differ in mass, size and many other chemical or physical properties. However, this is not correct for all situations. For example, Argon (Ar) and Calcium (Ca) atoms, each have an atomic mass of 40 amu. These atoms with similar atomic masses are isobars.

4) Dalton Atomic Theory fails to explain the existence of allotropes. For example, Dalton atomic theory fails to explain the differences in properties of charcoal, graphite, and diamond (which are the allotropes of carbon).

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2 years ago

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What's the difference between electromagnetic waves and electromagnetic spectrum?

White raven [17]

The difference between the two is, well for one

Spectrum: The entire range that the "<em>waves" </em>could be such, as visible light, x-ray's and so on.

Waves: These are different because they aren't telling you or showing the entire spectrum just which they length that they are.

<em>It may confuse you but it makes sense to me (Sorry)</em>

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2 years ago

A 500 W hair dyer is used to dry hair for 6 minutes a day for 3 days. How much energy is used? A laptop uses 75 W. The cot of el

zzz [600]

Answer:

See the answers below.

Explanation:

We will solve this problem by calculating each part separately.

A 500 W hair dyer is used to dry hair for 6 minutes a day for 3 days.

Energy can be calculated by multiplying the value of the power of the equipment by the amount of time of use.

$500 [W]*[\frac{6min}{1day} ]*[\frac{1day}{24hr} ]*[\frac{1hr}{60min} ]=2.083 [W]$

The cots of electricity is 5.6 cents per kWh. How much would it cost to operate the laptop for 24 hours a day for one week?

We know that the power of the latop is 75 [W], then we can calculate the cost, multiplying the value of the power by the value of the cost by the time of use of the computer.

$0.075[kW]*5.6[\frac{cents}{kw*h}}]*[\frac{24hr}{1day}]*[1week]*[\frac{7days}{1week} ]=70.56 [cents]$

A toaster oven is 85% efficient. It uses 1200 J of energy. How much thermal energy is it producing?

Efficiency is defined as the relationship between the energy obtained on the energy delivered. Almost always the energy delivered is greater than the energy obtained (first law of thermodynamics).

Therefore.

$Effic = E_{obtained}/E_{delivered}\\0.85=E_{obtained}/1200\\E_{obtained}=1020[J]$

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2 years ago