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4 years ago

Can someone help me plzit's a glass bell jar and to vacuum pump

Physics

1 answer:

Nata [24]4 years ago

7 0

A) the pump removes air from the enclosure. foam absorbs vibrations from the clock
b) result is that as the air is taken out by pump, the sound of alarm reduces and eventually becomes zero. so, you cant hear the alarm ringing.
c) conclusion is that sound cant travel in vaccum and it requires a medium to travel.

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A cold beverage can be kept cold even a warm day if it is slipped into a porous ceramic container that has been soaked in water.

Arisa [49]

Answer:

The rate at which the container is losing water is 0.0006418 g/s.

Explanation:

Under the assumption that the can is a closed system, the conservation law applied to the system would be: $E_{in}-E_{out}=E_{change}$ , where $E_{in}$ is all energy entering the system, $E_{out}$ is the total energy leaving the system and, $E_{change}$ is the change of energy of the system.
As the purpose is to kept the beverage can at constant temperature, the change of energy ( $E_{change}$ ) would be 0.
The energy that goes into the system, is the heat transfer by radiation from the environment to the top and side surfaces of the can. This kind of transfer is described by: $Q=\varepsilon*\sigma*A_S*(T_{\infty}^4-T_S^4)$ where $\varepsilon$ is the emissivity of the surface, $\sigma=5.67*10^{-8}\frac{W}{m^2K}$ known as the Stefan–Boltzmann constant, $A_S$ is the total area of the exposed surface, $T_S$ is the temperature of the surface in Kelvin, $T_{\infty}$ is the environment temperature in Kelvin.
For the can the surface area would be ta sum of the top and the sides. The area of the top would be $A_{top}=\pi* r^2=\pi(0.0252m)^2=0.001995m^2$ , the area of the sides would be $A_{sides}=2*\pi*r*L=2*\pi*(0.0252m)*(0.09m)=0.01425m^2$ . Then the total area would be $A_{total}=A_{top}+A_{sides}=0.01624m^2$
Then the radiation heat transferred to the can would be $Q=\varepsilon*\sigma*A_S*(T_{\infty}^4-T_S^4)=1*5.67*10^{-8}\frac{W}{m^2K}*0.01624m^2*((32+273K)^4-(17+273K)^4)=1.456W$ .
The can would lost heat evaporating water, in this case would be $Q_{out}=\frac{dm}{dt}*h_{fg}$ , where $\frac{dm}{dt}$ is the rate of mass of water evaporated and, $h_{fg}$ is the heat of vaporization of the water ( $2257\frac{J}{g}$ ).
Then in the conservation balance: $Q_{in}-Q_{out}=Q_{change}$ , it would be $1.45W-\frac{dm}{dt}*2257\frac{j}{g}=0$ .
Recall that $1W=1\frac{J}{s}$ , then solving for $\frac{dm}{dt}$ : $\frac{dm}{dt}=\frac{1.45\frac{J}{s} }{2257\frac{J}{g} }=0.0006452\frac{g}{s}$

5 0

3 years ago

Sally goes on a hike. The distance she walks compared to the amount of time she walks is shown on the graph. Which statement is

Neko [114]

According to the task there should be the graph that supports Sally's hike, but after looking on the options it seems that Sally doesn't walks at a constant rate and there is the negative option that coincides with my thoughts. So, I bet the false statement is the third option represented in the scale above.

5 0

3 years ago

Explain the difference between science usage and common usage for the term resistance

san4es73 [151]

Keremiad<span> is a long literary work, usually in prose, but sometimes in verse, in which the author bitterly laments the state of society and its morals in a serious tone of sustained invective, and always contains a prophecy of society's imminent downfall. </span>

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3 years ago

I need help someone help me

GaryK [48]

what do you need , i mean your help , let me see if i can help

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3 years ago

The light energy that falls on a square meter of ground over the course of a typical sunny day is about 20 MJ . The average rate

Sphinxa [80]

86.4×10^6 joule is energy does one house use during each 24 hr day.

20 MJ of light energy

Consumption of electricity is 1 kW.

The energy consumption lasts for 24 hours.

energy=power×time

energy=10^3×24×3600

energy=86.4×10^6 joule

Energy in physics is the ability to perform work. Different shapes, such as potential, kinetic, thermal, electrical, chemical, radioactive, etc., may be assumed by it. Other examples of energy being transferred from one body to another include heat and work. Energy is always distributed after it has been transported in accordance with its type. Thus, heat transfer could result in thermal energy, whereas work could result in mechanical energy.

Motion is a trait shared by all forms of energy. For instance, if a body is moving, it has kinetic energy. Due to the object's design, which incorporates potential energy, a tensioned object, like a spring or bow, has the ability to move even when at rest.

To know more about energy visit : brainly.com/question/1932868

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1 year ago