Melting, boiling, anf bending are physical changes but why is burning a chemical change

Physics

2 answers:

bija089 [108]4 years ago

7 0

Because burning is a non-reversible chemical change.

Nady [450]4 years ago

6 0

Burning is a chemical change because if it flames it could not back to the way it was it will be ash. Plus to start a fire with a lighter that has a chemical liquid that makes it flammable.

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The p wave on an electrocardiogram represents __________.

Harrizon [31]

It represents the depolarization of the atria.

Explanation:

The P wave speaks to the depolarization of the left and right chamber and furthermore relates to atrial compression. Carefully, the atria contract a brief moment after the P wave starts. Since it is so little, atrial repolarization is typically not unmistakable on ECG.

In an ordinary ECG, there's three particular waves. The primary wave is the P wave, which speaks to the depolarization of the atria. This happens directly before the atria agreement and drive blood into the ventricles. The following wave is known as the QRS wave.

3 0

3 years ago

A rocket is fired with an initial VELOCITY OF 100m/s at an angle of 55° above the horizontal, It explodes On the mountain Side 1

GuDViN [60]

Answer

688.32m and 277.44m

Explanation :

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$\large{\maltese{\textsf{\underline{To find :-}}}}$

The X and Y coordinates of the rocket relative of firing

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$\large{\maltese{\textsf{\underline{Given :-}}}} \\ \\ \sf velocity (v_i) = 100m{s}^{-1} \\ \sf angle ({\theta}_{1}) = 55.0{\degree} \\ \sf time (t) = 12s$

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$\Large{\maltese{\textsf{\underline{\underline{Step by Step Solution:-}}}}}$

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The horizontal range of projectile at x.

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$\sf \large{x = v_{xi}} \times t \\ \\ \sf \large{x = v_i \times \cos {\theta}_{i} \times t}$

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$\large\textsf{\underline{Now substituting the required values}}$

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$\sf x = 300 \times \cos 55{\degree} \times 12 \\ \\ \sf x = 100 \times 0.5756 \times 12 \\ \\ {\underline{\boxed{\bold{ x = 688.32m}}}}$

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The vertical position of projectile at y.

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$\sf \large y = v_{yi} \times t - (\frac{1}{2} \times g \times {t}^{2}) \\ \\ \sf \large y = v_i \times \cos \theta \times t - \frac{1}{2} g {t}^{2}$

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$\textsf{ \large {\underline{Now substituting the required values}} }$

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$\sf y = 100 \times \cos55{ \degree} \times 12 - \frac{1}{2} \times 9.80 \times {12}^{2} \\ \\ \sf y = 100 \times 0.8192 \times 12 - 0.5 \times 9.8 \times 144 \\ \\ \sf y = 983.04 - 705.6 \\ \\ \underline{ \boxed{ \bold{y = 277.44m}}}$