Yo can someone find me an e-boy?

During the era of known as the Stone Age, no tools were used and no technology was created.

Shtirlitz [24]

Answer:

stone wheel

Explanation:

it was built around 3500 B.C.

5 0

4 years ago

Mechanical clips are used to close bags and keep things together. Investigate the design of various paper clips, hair clips, and

pochemuha

Answer:

Hair clip: this used to hold human hairs together especially long hairs

The Design parameters to be considered are : number of teeth, durability of the material to be used and also the width ( how wide the clip can open )

Advantages : very easy to use, holds hairs tight

Disadvantages : Expensive and material used is sometimes brittle

paper clips : This used to hold papers together it is made of a thin elastic wire

The design parameters to be considered are : length of the wire, material to be used and the elasticity of the material

advantages : it is quite cheap and good strength

disadvantages :it can hold a limited amount of papers together

potato chip bag clips: These clips are used on potato chip bags to ensure that the bags are air tight

The design parameters to be considered are : Elasticity of the material to be used , and size

Advantages : it helps to prevent the potato chips from getting exposed to air

disadvantages : Not very popular and its quite expensive

Explanation:

Hair clip: this used to hold human hairs together especially long hairs

The Design parameters to be considered are : number of teeth, durability of the material to be used and also the width ( how wide the clip can open )

Advantages : very easy to use, holds hairs tight

Disadvantages : Expensive and material used is sometimes brittle

paper clips : This used to hold papers together it is made of a thin elastic wire

The design parameters to be considered are : length of the wire, material to be used and the elasticity of the material

advantages : it is quite cheap and good strength

disadvantages :it can hold a limited amount of papers together

potato chip bag clips: These clips are used on potato chip bags to ensure that the bags are air tight

The design parameters to be considered are : Elasticity of the material to be used , and size

Advantages : it helps to prevent the potato chips from getting exposed to air

disadvantages : Not very popular and its quite expensive

4 0

3 years ago

The minimum fresh air requirement of a residential building is specified to be 0.35 air changes per hour (ASHRAE, Standard 62, 1

Thepotemich [5.8K]

Answer:

a) The flow capacity of the fan is 3150 L/min

d) the minimum diameter is 0.11 m

Explanation:

given data:

A = area of residence = 200 m²

h = height of building = 2.7 m

Percentage of air that must be replaced by fresh air is 35%

v = velocity of air in the duct = 5.5 m/s

a) The volume of the entire building is:

$Volume=2.7*200=540m^{3}$

The flow capacity of the fan is equal to:

$Flow=\frac{0.35*540}{60} =3.15m^{3} /min$

$Flow=3.15\frac{m^{3} }{min} *\frac{1000L}{1m^{3} } =3150L/min$

b) The volume flow rate of fresh air is equal to:

$Flow=\frac{\pi *d^{2} }{4} V\\d=\sqrt{\frac{4*Flow}{\pi V} } =\sqrt{\frac{4*3.15}{\pi *5.5*60} } =0.11m$

6 0

4 years ago

WHAT IS MEANT BY BJT AND FUNCTION OF BJT

Andrej [43]

Answer:

A Bipolar Junction Transistor, or BJT, is a solid-state device in which the current flow between two terminals (the collector and the emitter) is controlled by the amount of current that flows through a third terminal (the base).

The main basic function of a BJT is to amplify current it will allow BJTs are used as amplifiers or switches to produce wide applicability in electronic equipment include mobile phones, industrial control, television, and radio transmitters. There are two different types of BJTs are available, they are NPN and PNP.

8 0

3 years ago

The heat flux through a 1-mm thick layer of skin is 1.05 x 104 W/m2. The temperature at the inside surface is 37°C and the tempe

miss Akunina [59]

Answer:

a) Thermal conductivity of skin: $k_{skin}=1.5W/mK$

b) Temperature of interface: $T_{interface}=35.6\°C$

Heat flux through skin: $\frac{Q}{A}=2100W/m^2$

Explanation:

a)

$k=\frac{QL}{A(T_{2}-T_{1})}$

Where: $k$ is thermal conductivity of a material, $\frac{Q}{A}$ is heat flux through a material, $L$ is the thickness of the material, $T_{1}$ is the temperature on the first side and $T_{2}$ is the temperature on the second side