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coldgirl [10]
3 years ago
13

Define what a glass transition is and what happens to a polymer because of it

Engineering
1 answer:
lesya692 [45]3 years ago
7 0

Answer:

 The glass transition occur when the given temperature gets drop below the temperature of the glass transition for the polymers. During the creases of the long range of the given motion, the polymer start changing from the state of hard into the form of brittle.

The range of the glass transition temperature are between the 0 to -150°C. The basic use of the polymer is basically depend upon the main properties of the polymer.

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Methane gas is 304 C with 4.5 tons of mass flow per hour to an uninsulated horizontal pipe with a diameter of 25 cm. It enters a
Arada [10]

Answer:

a) h_c = 0.1599 W/m^2-K

b) H_{loss} = 5.02 W

c) T_s = 302 K

d) \dot{Q} = 25.125 W

Explanation:

Non horizontal pipe diameter, d = 25 cm = 0.25 m

Radius, r = 0.25/2 = 0.125 m

Entry temperature, T₁ = 304 + 273 = 577 K

Exit temperature, T₂ = 284 + 273 = 557 K

Ambient temperature, T_a = 25^0 C = 298 K

Pipe length, L = 10 m

Area, A = 2πrL

A = 2π * 0.125 * 10

A = 7.855 m²

Mass flow rate,

\dot{ m} = 4.5 tons/hr\\\dot{m} = \frac{4.5*1000}{3600}  = 1.25 kg/sec

Rate of heat transfer,

\dot{Q} = \dot{m} c_p ( T_1 - T_2)\\\dot{Q} = 1.25 * 1.005 * (577 - 557)\\\dot{Q} = 25.125 W

a) To calculate the convection coefficient relationship for heat transfer by convection:

\dot{Q} = h_c A (T_1 - T_2)\\25.125 = h_c * 7.855 * (577 - 557)\\h_c = 0.1599 W/m^2 - K

Note that we cannot calculate the heat loss by the pipe to the environment without first calculating the surface temperature of the pipe.

c) The surface temperature of the pipe:

Smear coefficient of the pipe, k_c = 0.8

\dot{Q} = k_c A (T_s - T_a)\\25.125 = 0.8 * 7.855 * (T_s - 298)\\T_s = 302 K

b) Heat loss from the pipe to the environment:

H_{loss} = h_c A(T_s - T_a)\\H_{loss} = 0.1599 * 7.855( 302 - 298)\\H_{loss} = 5.02 W

d) The required fan control power is 25.125 W as calculated earlier above

5 0
3 years ago
One or more parties may terminate an agency relationship by placing into the agreement a time period for termination. When that
iVinArrow [24]

Answer:

Explanation:

Complete question:

Fill in the blanks

One or more parties may terminate an agency relationship by placing into the agreement a time period for termination. When that time ,___1______the agency ends. In addition, the parties can specify that the agency is for a particular____2______ . Once that is achieved, the agency ends. Alternatively, the parties can include a specific event as a trigger for termination; once that event,_____3______ the agency ends. The parties can terminate an agency relationship prior to any of the preceding events by ______4_________agreement, or revocation_____5______ by individual party.

Answer

1) lapses

(2) purpose

(3) occurs / begins

(4) mutual

(5) either

8 0
3 years ago
An axial compressive load of 708 kN is applied to a cylindrical component, 81 mm in diameter and 418 mm long, made of aluminium.
dalvyx [7]

Answer:

The compressive stress of aplying a force of 708 kN in a 81 mm diamter cylindrical component is 0.137 kN/mm^2 or 137465051 Pa (= 137.5 MPa)

Explanation:

The compressive stress in a cylindrical  component can be calculated aby dividing the compressive force F to the cross sectional area A:

fc= F/A

If the stress is wanted in Pascals (Pa), F and A must be in Newtons and square meters respectively.

For acylindrical component the cross sectional area A is:

A=πR^

If the diameter of the component is 81 mm, the radius is the half:

R=81mm /2 = 40.5 mm

Then A result:

A= 3.14 * (40.5 mm)^2  = 5150.4 mm^2

In square meters:

A= 3.14 * (0.0405 m)^2  = 0.005150 m^2

Replacing 708 kN to the force:

fc= 708 kN / 5150.4 mm^2 = 0.137 kN/mm^2

Using the force in Newtons:

F= 70800 N

Finally the compressive stress in Pa is:

fc= 708000 / 0.005150 m^2 = 137465051 Pa = 137 MPa

4 0
3 years ago
A man releases a stone (at rest, Vo=0) from the top of a tower. During the last second of its travel, the stone falls through a
RideAnS [48]

Answer:

Height of tower equals 122.5 meters.

Explanation:

Since the height of the tower is 'H' the total time of fall of stone 't' is calculated using second equation of kinematics as

Since the distance covered in last 1 second is \frac{9H}{25} and the total distance covered in 't' seconds is 'H' thus the distance covered in the first (t-1) seconds of the motion equals

S_{t-1}=S_{t}-S_{last}\\\\S_{t-1}=H-\frac{9H}{25}=\frac{16H}{25}

Now by second equation of kinematics we have

S=ut+\frac{1}{2}gt^{2}\\\\S=\frac{1}{2}gt^{2}(\because u=0)

Thus we have

\frac{16H}{25}=\frac{1}{2}g(t-1)^{2}.............(i)\\\\H=\frac{1}{2}gt^{2}..............(ii)

Dividing i by ii we get

\frac{16}{25}=\frac{(t-1)^{2}}{t^2}\\\\\therefore \frac{t-1}{t}=\frac{4}{5}\\\\\therefore t=5secs

Thus from equation ii we obtain 'H' as

H=\frac{1}{2}\times 9.8\times 5^{2}=122.5meters

6 0
3 years ago
Question #4
inn [45]

Answer:

Deconstruction

Explanation:

8 0
3 years ago
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