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3 years ago

11

Technician A says that ultraviolet light is bright, and very hot. Technician B says that ear protection does not need to be used

when welding. Who is correct?
a. Technician A only
b. Technician B only
c. Both Technicians A and B
d. Neither Technician A nor B

1 answer:

-Dominant- [34]3 years ago

3 0

Answer:

a. technician a only

Explanation:

I took that worksheet

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why is the thermal conductivity of super insolation order of magnitude lower than the thermal conductivity of ordinary insulatio

Anni [7]

Answer:

Super insulation are obtained by using layers of highly reflective sheets separated by glass fibers in an vacuumed space. Radiation heat transfer between any of the surfaces is inversely proportional to the number of sheets used and thus heat lost by radiation will be very low by using these highly reflective sheets which will an effective way of heat transfer.

Explanation:

3 0

3 years ago

What is the definition of a duty cycle?

ira [324]

Answer:

$D=\frac{PW}{T}*100$

Explanation:

In electrical terms, is the ratio of time in which a load or circuit is ON compared to the time in which the load or circuit is OFF.

The duty cycle or power cycle, is expressed as a percentage of the activation time. For example, a 70% duty cycle is a signal that 70% of the time is activated and the other 30% disabled. Its equation can be expressed as:

$D=\frac{PW}{T}*100$

Where:

$D=Duty\hspace{3}Cycle$

$PW=Pulse\hspace{3}Active\hspace{3}Time$

$T=Period\hspace{3}of\hspace{3}the\hspace{3}Signal$

Here is a picture that will help you understand these concepts.

5 0

3 years ago

A composite wall is to be used to insulate a freezer chamber at -350C. Two insulating materials are to be used with conductiviti

choli [55]

Answer:

thickness1=1.4m

thickness2=2.2m

convection coefficient=0.33W/m^2K

Explanation:

you must use this equation to calculate the thickness:

L=K(T2-T1)/Q

L=thickness

T=temperature

Q=heat

L1=0.04*(0--350)/10=1.4m

L2=0.1(220-0)/10=2.2m

Then use this equation to calculate the convective coefficient

H=Q/(T2-T1)

H=10/(250-220)=0.33W/m^2K

7 0

3 years ago

Kerosene flows through 3/4 standard type K drawn copper tube. The pressure drop measured at two points 50 m apart is 130 kPa. De

jok3333 [9.3K]

Answer:

$Q=4.98\times 10^{-3}\ m^3/s$ .

Explanation:

Given that

L= 50 m

Pressure drop = 130 KPa

copper tube is 3/4 standard type K drawn tube.

From standard chart ,the dimension of 3/4 standard type K copper tube given as

Outside diameter=22.22 mm

Inside diameter=18.92 mm

Dynamic viscosity for kerosene

$\mu =0.00164\ Pa.s$

We know that

$\Delta P=\dfrac{128\mu QL}{\pi d_i^4}$

Where Q is volume flow rate

L is length of tube

$d_i$ is inner diameter of tube

ΔP is pressure drop

μ is dynamic viscosity

Now by putting the values

$\Delta P=\dfrac{128\mu QL}{\pi d_i^4}$

$130\times 1000=\dfrac{128\times 0.00164\times 50Q}{\pi \times 0.01892^4}$

$Q=4.98\times 10^{-3}\ m^3/s$

So flow rate is $Q=4.98\times 10^{-3}\ m^3/s$ .

6 0

2 years ago

A garden hose fills a 2-gallon bucket in 5 seconds. The number of gallons, g (y), is proportional to the number of seconds, t (x

stepladder [879]

Answer:

0.4 gallons per second

Explanation:

A function shows the relationship between an independent variable and a dependent variable.

The independent variable (x values) are input variables i.e. they don't depend on other variables while the dependent variable (y values) are output variables i.e. they depend on other variables.

The rate of change or slope or constant of proportionality is the ratio of the dependent variable (y value) to the independent variable (x value).

Given that the garden hose fills a 2-gallon bucket in 5 seconds. The dependent variable = g = number of gallons, the independent variable = t = number of seconds.

Constant of proportionality = g / t = 2 / 5 = 0.4 gallons per second

5 0

3 years ago