When paper burns, some of the chemical compounds in the
paper combine with oxygen in the air and become different
chemical compounds. That's a chemical change.

When iron rusts, or copper or silver turns green, that's the result
of the metal at the surface combining with the oxygen in the air and
forming a new chemical compound. Those are chemical changes.

When water evaporates, H₂O in the liquid phase gains thermal
energy and changes to H₂O in the gaseous phase. No chemical
compounds are lost, gained, or changed to other compounds.
It's just a physical change.

6 0

2 years ago

The valu

natulia [17]

Answer:

$\% Error = 2.6\%$

Explanation:

Given

$x: 1.54, 1.53, 1.44, 1.54, 1.56, 1.45$

Required

Determine the percentage error

First, we calculate the mean

$\bar x = \frac{\sum x}{n}$

This gives:

$\bar x = \frac{1.54+ 1.53+ 1.44+ 1.54+ 1.56+ 1.45}{6}$

$\bar x = \frac{9.06}{6}$

$\bar x = 1.51$

Next, calculate the mean absolute error (E)

$|E| = \sqrt{\frac{1}{6}\sum(x - \bar x)^2}$

This gives:

$|E| = \sqrt{\frac{1}{6}*[(1.54 - 1.51)^2 +(1.53- 1.51)^2 +.... +(1.45- 1.51)^2]}$

$|E| = \sqrt{\frac{1}{6}*0.0132}$

$|E| = \sqrt{0.0022}$

$|E| = 0.04$

Next, calculate the relative error (R)

$R = \frac{|E|}{\bar x}$

$R = \frac{0.04}{1.51}$

$R = 0.026$

Lastly, the percentage error is calculated as:

$\% Error = R * 100\%$

$\% Error = 0.026 * 100\%$

$\% Error = 2.6\%$

4 0

3 years ago

As you finish listening to your favorite compact disc (CD), the CD in the player slows down to a stop. Assume that the CD spins

Colt1911 [192]

Answer:

A. $w=8.3rev/s$

$a_v=3.21rev/s^2$

B. rev=10.79rev

Explanation:

500rpm

$500rpm*\frac{1minute}{60seg}=8.33\frac{rev}{s}$

the time is about 2.60s knowing the acceleration is:

$a_v=\frac{w}{t}$

so:

$w=8.3rev/s$

$a_v=\frac{8.33 rev/s}{2.60s}=3.21rev/s^2$

The CD stop so the final velocity is vf=0 so:

Total revolutions:

$8.3rev/s*2.60s=21.58rev$

$21.58rev/2=10.79 rev$

3 0

3 years ago

Under which conditions do both convex and concave mirrors form virtual images? State whether or not each can form a real image.I

natali 33 [55]

Concave mirrors can make a real image.when the object is away from the mirror it is called real image and when the object is closer to the mirror it is called virtual mirror.

8 0

3 years ago

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