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Veseljchak [2.6K]
2 years ago
14

How could you know that a chemical change has taken place?

Physics
2 answers:
Contact [7]2 years ago
5 0

Answer:

There are five signs of a chemical change:

Color Change.

Production of an odor.

Change of Temperature.

Evolution of a gas (formation of bubbles)

Precipitate (formation of a solid)

Explanation: brainliest please

timama [110]2 years ago
5 0
There's at least one new substance there, that wasn't there before.

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An aircraft flying at a steady velocity of 70 m/s eastwards at a height of 800 m drops a package of supplies.
iren2701 [21]

The motion of the package can be described as the motion of a projectile,

given that it has an horizontal velocity and it is acted on by gravity.

  • a) \vec{v} = 70·i
  • b) The package will reach ground in approximately <u>12.77 seconds</u>.
  • c) The speed of the package as it lands is approximately <u>145.51 m/s</u>.
  • d) The path of the package based on a stationary frame of reference is <u>parabolic</u>
  • e) The path of the package as seen from the plane is <u>directly vertical</u> downwards

Reasons:

Velocity of the aircraft = 70 m/s

Direction of flight of the aircraft = Eastward

Height from which the aircraft drops the package, h = 800 m

a) The initial velocity of the package, \vec{v} = 70·i

b) The time it will take the package to reach the ground, <em>t</em>, is given by the formula;

\displaystyle h = \mathbf{\frac{1}{2} \cdot g \cdot t^2}

Where;

g = The acceleration due to gravity ≈ 9.81 m/s²

Therefore;

\displaystyle t = \mathbf{\sqrt{ \frac{2 \cdot h}{g} }}

Which gives;

\displaystyle t = \sqrt{ \frac{2 \times 800}{9.81} } \approx \mathbf{12.77}

The time it will take the package to reach the ground, t ≈ <u>12.77 seconds</u>

c) The vertical velocity just before the package reaches the ground, v_y, is given as follows;

v_y^2 = 2·g·h

Therefore;

v_y = √(2·g·h)

Which gives;

v_y = √(2 × 9.81 × 800) ≈ 125.28

v_y ≈ 125.28 m/s

Which gives; \vec{v} = 70·i - 125.28·j

Therefore, |v| = √(70² + (-125.28)²) ≈ 143.51

The speed of the package as it lands, |v| ≈ <u>143.51 m/s</u>

d) The motion of the package that includes both horizontal and vertical motion is a projectile motion.

Therefore;

The path of the package is the path of a projectile, which is a <u>parabolic shape</u>.

e) As seen by someone on the aeroplane, the horizontal velocity will be

zero, therefore, the package will appear as accelerating <u>directly vertical</u>

downwards.

Learn more about projectile motion here:

brainly.com/question/1130127

6 0
2 years ago
What are some forces acting on you now that you can't see? PLS HELP!!!!!!
RideAnS [48]

also displayed the effects of sound being an invisible force of our world. Sound are frequencies. Different frequencies shape matter differently as you’ve seen.

Now, the human ear can only hear frequencies to a certain extent. When you take a hearing test at the doctors, they test your hearing by playing different tones (frequencies) in your ear. As people get older they will not be able to hear higher frequencies.

6 0
3 years ago
Read 2 more answers
Think of a way you could demonstrate elastic force to a younger student. Describe the procedure you would follow and the materia
Soloha48 [4]

Answer:

I feel like to demonstrate you would use an elastic band as the material. You obviously have to put force in order to see how far it stretches. From this you can also find about its resistance and durability

Also you have to make sure the distance between the two hands are equal as you want an accurate result.

7 0
3 years ago
until a train is a safe distance from the station, it must travel at 5 m/s. Once the train is on open track , it can speed up to
kiruha [24]

Answer:

5

Explanation:

6 0
3 years ago
Please need help on this
Rasek [7]

Im pretty sure this is A. i may be incorrect, give brainliest if im correct please!

7 0
4 years ago
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