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2 years ago

Hiện tượng lọc và siêu lọc

Physics

1 answer:

STALIN [3.7K]2 years ago

7 0

Answer:

Siêu lọc (UF) là một dạng lọc màng trong đó các lực như áp suất hoặc gradient nồng độ được phân tách thông qua một màng bán thấm. Chất rắn lơ lửng và chất tan có trọng lượng phân tử cao được giữ lại trong cái gọi là retentate, trong khi nước và chất tan có trọng lượng phân tử thấp đi qua màng trong quá trình thẩm thấu (lọc). Quá trình tách này được sử dụng trong công nghiệp và nghiên cứu để tinh chế và cô đặc các dung dịch cao phân tử (103 106 Da), đặc biệt là các dung dịch protein.

Siêu lọc về cơ bản không khác gì vi lọc. Hai điều này khác nhau trên cơ sở loại trừ kích thước hoặc bắt giữ hạt. Điều này về cơ bản khác với sự phân tách khí qua màng, dựa trên tốc độ hấp thụ và khuếch tán khác nhau với số lượng khác nhau. Màng siêu lọc được xác định bằng trọng lượng phân tử (MWCO) của màng được sử dụng. Siêu lọc được thực hiện ở chế độ dòng chảy chéo hoặc dòng chết.

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In a 49 s interval, 595 hailstones strike a glass window of an area of 0.954 m at an angle of 25° to the window surface. Each ha

eduard

Average force on the window: 0.32 N

Explanation:

The average force exerted on the window is given by Newton's second law

$F=\frac{\Delta p}{\Delta t}$

where

$\Delta p$ is the net change in momentum of the hailstones in a time interval of $\Delta t$

In order to find the change in momentum, we have to consider only the component of the hailstone's momentum perpendicular to the window, therefore:

$p_i =m u sin \theta$ is the initial momentum of one hailstone, with

m = 7 g = 0.007 kg is the mass

$u=4.5 m/s$ is the initial speed

$\theta=25^{\circ}$ is the angle with the window

The final momentum is

$p_f = mv sin \theta$

where

v = 4.5 m/s is the final speed (the collision is elastic so the speed is equal, while the direction changes)

$\theta=-25^{\circ}$ (after the rebound, the direction has changed)

So the change in momentum of 1 hailstone is

$\Delta p = mv sin(-25^{\circ})-mu sin(25^{\circ})=-2mu sin(25^{\circ})=-0.0266 kg m/s$

We are interested only in the magnitude, so

$\Delta p = 0.0266 kg m/s$

There are 595 hailstones hitting the window in 49 s, so the total change in momentum is

$\Delta p = 595\cdot 0.0266 = 15.8 kg m/s$

And therefore, the average force on the window is

$F=\frac{\Delta p}{\Delta t}=\frac{15.8}{49}=0.32 N$

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2 years ago

A friend in your class tells you that she never uses hints when doing her Mastering homework. She says that she finds the hints

AnnZ [28]

Answer:

A, B, and C are good reasons for my friend not to worry

Explanation:

The following reasons are reason not to worry

A. The only way to lose additional partial credit on a hint is by using the "give up" button or entering incorrect answers. Leaving the question blank will not cost you any credit (Regardless of whether you open a link or not, you will lose credit if you enter a wrong answer or if you give up on a question by hitting the "give up" button. Even after opening a hint, you can leave the question blank if the hint does not provide relevant hints or if the hint brings up more question. Once the question is left blank, you do not lose additional partial credit)

B. As an incentive for thinking hard about the problem, your instructor may choose to apply a small hint penalty, but this penalty is the same whether the hint simply gives information or asks another question (In a situation where you decide to use a hint, the instructor may have put a penalty for using the hint, so whether it asks a question or help in the solution of the question, as long as the hint is consulted, the hint penalty still applies)

C. Getting the correct answer to the question in a hint actually gives you some partial credit, even if you still can't answer the original question (An advantage of using hint is that you get some partial credit for using it if you answer the hint question correctly and fails to answer the original question)

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3 years ago

brainly a child on a swing set swings back and forth with a period of 3.3 s and an amplitude of 25°. what is the maximum speed o

beks73 [17]

Maximum speed of the child as she swings is 2.23 m/s.

<h3>Step by Step Calculation:</h3>

T=3.3 s is the oscillation's time period.

The swing's greatest angle is 25° (max).

The swing's bottom will have the following kinetic energy:

k=12mv2...........(1)

The mass in this situation is m, and the speed is v.

The potential energy change is expressed as,

∆U=mgL1-cosθmax...............(2)

Here, L is a string's length and g is the acceleration caused by gravity. L is given as,

L=gT24π2

Combine equation (1) with (2)

12mv2=mgL1-cos, maxv=2g, maxv=gT24, maxv=g2T22, maxv=9.8 m/s

22.33 m/s, 22.31 s22.31 cos25°

Therefore, the child's top speed is 2.23 m/s.

<h3>What is Oscillation ?</h3>

The process of any quantity or measure fluctuating repeatedly about its equilibrium value in time is known as oscillation.
A periodic change in a substance's value between two values or around its central value is another way to define oscillation.

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1 year ago

Why should a physical quantity be measured?

Natasha_Volkova [10]

Answer:

It allows us to understand nature much more deeply than does qualitative description alone.

Explanation:

Without explaining the measurements, a quantity cannot always be measured.

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2 years ago

2. 3. 4. 5. 6. 7. A(n)results when a vehicle loses part or all of its grip on the road. is a technique that can be applied when

dexar [7]

Answer:

1) Skid

2)<u> </u>Rocking

3) Oversteer situation

4) Controlled breaking

5) Overdriving headlights

6) Hydroplaning

7) Understeer situation

Explanation:

1) A <u>skid</u> results when a vehicle loses part or all of its grip on the road

2)<u> Rocking</u> is a technique that can be applied when trying to move your vehicle out of deep snow

3) The action of vehicle's rear end sliding out to a side is called an <u>oversteer situation</u>

4) <u>Controlled breaking</u> is a technique of reducing your speed as quick as possible while maintaining control of your vehicle

5) Driving at a speed where the stopping distance of your vehicle is longer than the distance you can see with your headlights is called <u>overdriving headlights</u>

6) <u>Hydroplaning</u> occurs when a tire loses road surface contact and rises on top of water

7) It is an <u>understeer situation</u> when your front tires begin to plow and your vehicle is not responding or not responding as quickly as it should, to a steering point

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2 years ago