All categories

3 years ago

Studies show that chlorofluorocarbons (CFCs) such as CFC-12, are contributing to the depletion of the

Engineering

1 answer:

Pani-rosa [81]3 years ago

8 0

True .the chlorofluorocarbons also known as CFC’s also contribute on depleting the ozone layer

You might be interested in

. A line shaft rotating at 200 r.p.m. is to transmit 20 kW. The allowable shear stress for the material of the shaft is 42 MPa.

lbvjy [14]

Answer:

diameter=53.4 mm to 55 mm

Explanation:

7 0

3 years ago

How meny people live in new york

nydimaria [60]

Answer:

8.419 million (2019) at 2019

4 0

3 years ago

Find R subscript C and R subscript B in the following circuit such that BJT would be in the active region with V subscript C E e

Alex777 [14]

Answer: Rc = 400 Ω and Rb = 57.2 kΩ

Explanation:

Given that;

VCE = 5V

VCC = 15 V

iC = 25 mA

β = 100

VD₀ = 0.7 V

taking a look at the image; at loop 1

-VCC + (i × Rc) + VCE = 0

we substitute

-15 + ( 25 × Rc) + 5 = 0

25Rc = 10

Rc = 10 / 25

Rc = 0.4 k

Rc = 0.4 × 1000

Rc = 400 Ω

iC = βib

25mA = 100(ib)

ib = 25 mA / 100

ib = 0.25 mA

ib = 0.25 × 1000

ib = 250 μAmp

Now at Loop 2

-Vcc + (ib×Rb) + VD₀ = 0

-15 (250 × Rb) + 0.7 = 0

250Rb = 15 - 0.7

250Rb = 14.3

Rb = 14.3 / 250

Rb = 0.0572 μ

Rb = 0.0572 × 1000

Rb = 57.2 kΩ

Therefore Rc = 400 Ω and Rb = 57.2 kΩ

8 0

3 years ago

Consider a very long, cylindrical fin. The temperature of the fin at the tip and base are 25 °C and 50 °C, respectively. The dia

Mrrafil [7]

Answer:

The fin temperature in °C at a distance of 10 cm from the base = 33.78°C

Explanation:

The following assumptions will be made to solve this problem

- The heat transfer coefficient does not change with the time or distance.

- The temperature of the fins varies just in only one direction.

The temperature of the fin at x = 10 cm = 0.10 m from the base can be calculated from the temperature variation with distance formula for a very long fin.

(T - T∞) = (T₀ - T∞)e⁻ᵐˣ

T = T(x) = temperature at any point along the fin

T∞ = temperature at the tip of the fin = ambient temperature = 25°C

T₀ = temperature at the base of thw fin = 50°C

x = any distance along the length of the fin from the base of the fin = 0.1 m

m = √(hP/KA)

h = Heat transfer coefficient = 123 W/m².K

P = perimeter in contact with the base = πD = π × 0.03 = 0.0943 m

K = thermal conductivity = 150 W/m.K

A = surface area in contact with the base = πD²/4 = π(0.03)²/4 = 0.0007071 m²

m = √(123 × 0.0943)/(150 × 0.0007071)

m = 10.46

mx = 10.46 × 0.1 = 1.046

(T - 25) = (50 - 25) e⁻¹•⁰⁴⁶

T = 25 + 25 e⁻¹•⁰⁴⁶ = 25 + 8.78 = 33.78°C

8 0

3 years ago

Discuss why TVET Institutions need advice of the business community in order

Aliun [14]

Answer:

Without the indispensable advice of the business community, TVET Institutions will be unable to cover the gap in career knowledge required by the business community. To develop workers who possess the knowledge and skills required by today's business entities, there is always the continual need for the educational institutions (gown) to regularly meet the business community (town). This meeting provides the necessary ground for the institutions to develop programs that groom the workforce with skills that are needed in the current workplace. Educational institutions that do not seek this important advice from the business community risk developing workers with outdated skills.

Explanation:

TVET Institutions mean Technical and Vocational Education and Training Institutions. They play an important role in equipping young people to enter the world of work. They also continue to develop programs that will improve the employability of workers throughout their careers. They regularly respond to the changing labor market needs, adopt new training strategies and technologies, and expand the outreach of their training to current workers while grooming the young people for work.

4 0

3 years ago