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3 years ago

How do things rust? Is this chemical or mechanical weathering?

2 answers:

8 0

Rust is a type of iron oxide. When oxygen and a substance collide it creates oxides. This is a process called oxidation which is a type of chemical weathering.

IrinaK [193]3 years ago

6 0

I'll say that's mechanical weathering

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A 1.20-m cylindrical rod of diameter 0.570 cm is connected to a power supply that maintains a constant potential difference of 1

nasty-shy [4]

(a) $1.72\cdot 10^{-5} \Omega m$

The resistance of the rod is given by:

$R=\rho \frac{L}{A}$ (1)

where

$\rho$ is the material resistivity

L = 1.20 m is the length of the rod

A is the cross-sectional area

The radius of the rod is half the diameter: $r=0.570 cm/2=0.285 cm=2.85\cdot 10^{-3} m$ , so the cross-sectional area is

$A=\pi r^2=\pi (2.85\cdot 10^{-3} m)^2=2.55\cdot 10^{-5} m^2$

The resistance at 20°C can be found by using Ohm's law. In fact, we know:

- The voltage at this temperature is V = 15.0 V

- The current at this temperature is I = 18.6 A

So, the resistance is

$R=\frac{V}{I}=\frac{15.0 V}{18.6 A}=0.81 \Omega$

And now we can re-arrange the eq.(1) to solve for the resistivity:

$\rho=\frac{RA}{L}=\frac{(0.81 \Omega)(2.55\cdot 10^{-5} m^2)}{1.20 m}=1.72\cdot 10^{-5} \Omega m$

(b) $8.57\cdot 10^{-4} /{\circ}C$

First of all, let's find the new resistance of the wire at 92.0°C. In this case, the current is

I = 17.5 A

So the resistance is

$R=\frac{V}{I}=\frac{15.0 V}{17.5 A}=0.86 \Omega$

The equation that gives the change in resistance as a function of the temperature is

$R(T)=R_0 (1+\alpha(T-T_0))$

where

$R(T)=0.86 \Omega$ is the resistance at the new temperature (92.0°C)

$R_0=0.81 \Omega$ is the resistance at the original temperature (20.0°C)

$\alpha$ is the temperature coefficient of resistivity

$T=92^{\circ}C$

$T_0 = 20^{\circ}$

Solving the formula for $\alpha$ , we find

$\alpha=\frac{\frac{R(T)}{R_0}-1}{T-T_0}=\frac{\frac{0.86 \Omega}{0.81 \Omega}-1}{92C-20C}=8.57\cdot 10^{-4} /{\circ}C$

5 0

3 years ago

The movement of both oxygen and carbon dioxide in the body is accomplished by ___.

ad-work [718]

Answer: Diffusion

Explanation: Please give brainliest

7 0

3 years ago

Describe the mirror formula for a concave mirror in a shortcut way

sattari [20]

Answer:

1/f =1/v+1/u

Explanation:

4 0

3 years ago

How is friction reduced between an air hockey puck and the table.

iren2701 [21]

Answer:

An air hockey table has a very smooth and slippery surface which reduces friction by suspending the puck on cushion of air, so that this its motion is much less altered by friction, causing it to glide in a straight line at relatively constant velocity across the table.

Explanation:

6 0

3 years ago

You want to make a photo album for your friend. In three to five sentences, describe at least one advantage and one disadvantage

Eddi Din [679]

If you are choosing to get a digital photo album it can come with the advantages like, it’s more economically friendly because you’re not having to print out pictures. But it’s disadvantage is that you can lose it easily or accidentally delete it some way. You also have a choice of a physical photo album, it’s advantages are that you won’t lose it as easily and they might last longer than a digital one’s. It’s disadvantage though is that with all the pictures and the book to keep the pictures in takes a lot from the economy. A solution to the digital photo album is to save in on a hard drive or something like that so you can keep it without having to worry about it being deleted as easily. The solution with the physical photo album is that you could get a photo holder that you can slide picture into pockets because it will keep the pictures from damage as well as using less paper products.

you can read over it and change things i might have done wrong and if i completely missed the point of this i’m sorry and hope you have a good day/night. (also it’s 6 sentences)

6 0

3 years ago

Read 2 more answers