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3 years ago

Which of the following quantities is a scalar? I need help plz someone help me!!!!!

Physics

2 answers:

Colt1911 [192]3 years ago

5 0

'D' is the scalar. It has size but no direction. The other choices have directions too, so those are vectors.

SSSSS [86.1K]3 years ago

5 0

D is scalar because scalar quantities are on magnitude while vector quantities are magnitude and direction

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Which of the following statements about comets is true? A. Comets rarely fall into an orbit around the Sun. They usually enter t

GREYUIT [131]

<h2>Right answer: Comets have very elliptical orbits that usually take them far beyond the orbit of Pluto, but also take them closer to the Sun than Earth</h2>

Comets are celestial bodies constituted by ice, dust and rocks that orbit around the Sun, after having been altered by the Oort cloud; following different trajectories that can be <u>highly eccentric elliptical</u><u> </u>(periodic trajectories), parabolic or hyperbolic.

One of the main characteristics of a comet is that it travels quite fast, on its way around the Sun and has a long tail. It should be noted that the tails of comets always go in the opposite direction to the Sun (due to the radiation pressure of sunlight).

Therefore, the correct option is C.

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3 years ago

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It is correct to say that impulse is equal toA) momentum.B) the change in momentum.C) the force multiplied by the distance the f

goldenfox [79]

Answer:

B) the change in momentum

Explanation:

Impulse is defined as the product between the force exerted on an object (F) and the contact time ( $\Delta t$ )

$I=F \Delta t$

Using Newton's second law (F = ma), we can rewrite the force as product of mass (m) and acceleration (a):

$I=(ma) \Delta t$

However, the acceleration is the ratio between the change in velocity ( $\Delta v$ ) and the contact time ( $\Delta t$ ): $a=\frac{\Delta v}{\Delta t}$ , so the previous equation becomes

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And by simplifying $\Delta t$ ,

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3 years ago

Which statements describe how chemical formulas, such as H2O, represent compounds? Check all that apply.

Pani-rosa [81]

The statements that apply in this case are:

They show the elements that make up a compound.

They show the types of atoms that make up a molecule.

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3 years ago

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3. A concrete highway is built of slabs 12 m long (20o C). How wide should the expansion cracks between the slabs be (at 20o C)

lesantik [10]

Answer:

$\Delta x=2.304\times 10^{-2}\ m=2.304\ cm$ is the minimum gap between the slabs

Explanation:

Given:

length of the concrete highway, $l=12\ m$

coefficient of thermal expansion, $\alpha=12\times 10^{-6}\ ^{\circ}C^{-1}$

range of temperature variation, $(-30^{\circ}C\ to\ 50^{\circ}C) \Rightarrow \Delta T=80^{\circ}C$

<u>Now form the equation of thermal expansion:</u>

$\Delta l=l\times \alpha\times \Delta T$

$\Delta l=12\times (12\times 10^{-6})\times 80$

$\Delta l=1.152\times 10^{-2}\ m$

Since each slab of the highway expands by the above length so the minimum gap between the slabs to prevent buckling:

$\Delta x=2\times \Delta l$

$\Delta x=2\times( 1.152\times 10^{-2})$

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3 years ago

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scoray [572]

Answer: d. thunderstorms
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Thunderstorms happen more in summer because the rate of evaporation and condensation is increased.</span>

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3 years ago

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