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2 years ago

why is The sum of two vectors has the smallest magnitude when the angle between these two vectors is 180t

Physics

1 answer:

Effectus [21]2 years ago

8 0

Answer:

C = A - B

Explanation:

The addition of vectors takes into account the magnitude of each vector and its direction, so when adding two vectors, the result depends on the direction of the vectors.

* If the vectors have the same direction the result is maximum

C = A + A

* if the vectors have 90 between them, the magnitude of the result is given by the Pythagorean Theorem

C = √(A² + B²)

* if the vectors have 180º between them the result is minimal

C = A - B

We can also perform this sum graphically, where the resulting vector goes from the origin of the first vector to the tip of the last one, it can clearly be seen that when the vectors are antiparallel (180º angle) the magnitude is minimal

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You find it takes 200 J of heat to take 4 kg of an unknown substance from 200 K to 240 K. It does not change phases during this

klasskru [66]

Answer:

300 K

Explanation:

First, we have find the specific heat capacity of the unknown substance.

The heat gained by the substance is given by the formula:

H = m*c*(T2 - T1)

Where m = mass of the substance

c = specific heat capacity

T2 = final temperature

T1 = initial temperature

From the question:

H = 200J

m = 4 kg

T1 = 200K

T2 = 240 K

Therefore:

200 = 4 * c * (240 - 200)

200 = 4 * c * 40

200 = 160 * c

c = 200/160

c = 1.25 J/kgK

The heat capacity of the substance is 1.25 J/kgK.

If 300 J of heat is added, the new heat becomes 500 J.

Hence, we need to find the final temperature, T2, when heat is 500 J.

Using the same formula:

500 = 4 * 1.25 * (T2 - 200)

500 = 5 * (T2 - 200)

100 = T2 - 200

=> T2 = 100 + 200 = 300 K

The new final temperature of the unknown substance is 300K.

7 0

3 years ago

A power plant produces 1000 MW to supply a city 40 km away. Current flows from the power plant on a single wire of resistance 0.

nikitadnepr [17]

Answer:

Current = 8696 A

Fraction of power lost = $\dfrac{80}{529}$ = 0.151

Explanation:

Electric power is given by

$P=IV$

where I is the current and V is the voltage.

$I=\dfrac{P}{V}$

Using values from the question,

$I=\dfrac{1000\times10^6 \text{ W}}{115\times10^3\text{ V}} = 8696 \text{ A}$

The power loss is given by

$P_\text{loss} = I^2R$

where R is the resistance of the wire. From the question, the wire has a resistance of $0.050\Omega$ per km. Since resistance is proportional to length, the resistance of the wire is

$R = 0.050\times40 = 2\Omega$

Hence,

$P_\text{loss} = \left(\dfrac{200000}{23}\right)^2\times2$

The fraction lost = $\dfrac{P_\text{loss}}{P}=\left(\dfrac{200000}{23}\right)^2\times2\div (1000\times10^6)=\dfrac{80}{529}=0.151$

3 0

3 years ago

A material through which electrons can move easily is a what

kirill [66]

Answer:

Electrical conductors

3 0

11 months ago

A dancer starts 3 meters from the curtain then moves 8 meters from the curtain in 15 seconds. What was his velocity?

myrzilka [38]

I am pretty sure it is either 45 or 0.2

8 0

3 years ago

It is believed that increasing amounts of greenhouse gases in the atmosphere will result in

Jobisdone [24]

"Belief" is not involved.

<em>Choice-A</em> is the correct answer. Except that it's not "... will result in ...". It's already happening.

The people who have been keeping records of temperatures at a thousand places around the world, for the past hundred years, do not "believe". They know that average global temperatures are increasing, and have been increasing steadily for a couple of Centuries now.

Working from hypotheses, models, observations, and proven laws of nature, the global scientific community are convinced that increasing amounts of greenhouse gases in the atmosphere, driven by human activity, are the cause of the trend in average global temperatures.

Yes, you can find published researchers who aren't so sure, and who disagree with this conclusion. The scientific community is <em>never</em> 100% unanimous. There were reasonable investigators and scientific observers who disagreed with Galileo, Newton, Faraday, Maxwell, Hawking and Einstein, in their time.

But the voices that dispute human-caused climate change in the form of global warming are few, and they're becoming fewer as time goes on. Today, their reputation sits just a few notches above that of the Flat-Earthers, and it's continuing to sag further.

If we are to do what has to be done, in time to bring about the needed effect, it can't sag fast enough.

8 0

3 years ago