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Trava [24]
3 years ago
10

You volunteer for chalkboard cleaning duty and you get to work with the erasers. As you rub the dust off of the chalkboard, whit

e chalk dust enters the air and makes you cough. As you clean the chalkboard with the eraser, are you causing a physical change or a chemical change? Explain your answer.
Physics
1 answer:
Anna71 [15]3 years ago
3 0

Answer:

A physical change

Explanation:

You are wiping chalk particles from the board to the eraser which is just changing the location of the chalk particles, a physical change.

you're not changing the chalk into a new substance or causing a chemical reaction, which would be a chemical change.

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What happens to some of the sun's energy that does not reach the earth's surface?
LenaWriter [7]
Hello, 

Here is your answer:

The proper answer for this question is that they "get absorbed by the ozone layer".

If you need anymore help feel free to ask me!

Hope this helps!
4 0
2 years ago
A planet in elliptical orbit around a star moves from the point in its orbit furthest from the star (A) to the closest point (P)
Virty [35]

Answer:

Zero work done,since the body isn't acting against  or by gravity.

Explanation:

Gravitational force is usually  considered as work done against gravity (-ve) and work by gravity ( +ve ) and also When work isn't done by or against gravity work done in this case is zero.

Gravitational force can be define as that force that attracts a body to any other phyical body or system that have mass.

The planet been considered as our system in this case is assumed to have mass, and ought to demonstrate such properties associated with gravitational force in such system. Such properties include the return of every object been thrown up as a result of gravity acting downwards. The orbiting nature of object along an elliptical part when gravitational force isn't acting on the body and it is assumed to be zero.

6 0
3 years ago
A camera is equipped with a lens with a focal length of 34 cm. When an object 2.4 m (240 cm) away is being photographed, what is
puteri [66]

Answer:

The magnification is -6.05.

Explanation:

Given that,

Focal length = 34 cm

Distance of the image =2.4 m = 240 cm

We need to calculate the distance of the object

\dfrac{1}{u}+\dfrac{1}{v}=\dfrac{1}{f}

Where, u = distance of the object

v = distance of the image

f = focal length

Put the value into the formula

\dfrac{1}{u}=\dfrac{1}{34}-\dfrac{1}{240}

\dfrac{1}{u}=\dfrac{103}{4080}

u =\dfrac{4080}{103}

The magnification is

m = \dfrac{-v}{u}

m=\dfrac{-240\times103}{4080}

m = -6.05

Hence, The magnification is -6.05.

6 0
2 years ago
Which are characteristics of electromagnetic waves?check all that apply.
emmainna [20.7K]

Correct choices are marked in bold:

travel in straight lines and can bounce off surfaces  --> TRUE, normally electromagnetic waves travel in straight lines, however they can be reflected by objects, bouncing off their surfaces

travel through space at the speed of light  --> TRUE, all electromagnetic waves in space (vacuum) travel at the speed of light, c=3\cdot 10^8 m/s)

travel only through matter  --> FALSE; electromagnetic waves can also travel through vacuum

travel only through space  --> FALSE, electromagnetic waves can also travel through matter

can bend around objects  --> TRUE, this is what happens for instance when diffraction occurs: electromagnetic waves are bended around obstacles or small slits

move by particles bumping into each other  --> FALSE, electromagnetic waves are oscillations of electric and magnetic fields, so no particles are involved

move by the interaction between an electric field and a magnetic field --> TRUE, electromagnetic waves consist of an electric field and a magnetic field oscillating in a direction perpendicular to the direction of motion of the wave

8 0
3 years ago
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An infrared wave traveling through a vacuum has a frequency of 4.2
ololo11 [35]

Answer:O 7.1x10^-7 m

Explanation:

3 0
3 years ago
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