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2 years ago

7

Engineers designed a motorcycle helmet from a long-lasting and safe material that protects the wearer from accidents and excessi

ve heat. What is one technological design criterion that the engineers still need to meet

1 answer:

Mkey [24]2 years ago

3 0

kay flock accidents going crazy

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a solid circular shaft 150 mm diameter transmits a torque of 29820.586 N.m. find the maximum shear stress

bezimeni [28]

Answer:

45 Mpa

Explanation:

The maximum shear stress, $\tau_{max}$ is given by

$\tau_{max}=\frac {16T}{\pi d^{3}}$

Where T is the torque and d is the diameter.

Substituting 29820.586 N.m for T and 0.15m for d then we obtain

$\tau_{max}=\frac {16\times 29820.586}{\pi \times 0.15^{3}}=44999999.22\approx 45 Mpa$

4 0

4 years ago

Estimate the design-stage uncertainty in determining the voltage drop across an electric heating element. The device has a nomin

Volgvan

Answer:

Find the attachment for solution

Note: The resistance is measured in ohms (Ω). In the question Ω will replace V, where ever the resistance unit is required .

3 0

4 years ago

Refrigerant 134a at p1 = 30 lbf/in2, T1 = 40oF enters a compressor operating at steady state with a mass flow rate of 200 lb/h a

Mazyrski [523]

Answer:

a) $\mathbf{Q_c = -3730.8684 \ Btu/hr}$

b) $\mathbf{\sigma _c = 4.3067 \ Btu/hr ^0R}$

Explanation:

From the properties of Super-heated Refrigerant 134a Vapor at $T_1 = 40^0 F$ , $P_1 = 30 \ lbf/in^2$ ; we obtain the following properties for specific enthalpy and specific entropy.

So; specific enthalpy $h_1 = 109.12 \ Btu/lb$

specific entropy $s_1 = 0.2315 \ Btu/lb.^0R$

Also; from the properties of saturated Refrigerant 134 a vapor (liquid - vapor). pressure table at $P_2 = 160 \ lbf/in^2$ ; we obtain the following properties:

$h_2 = 115.91 \ Btu/lb\\\\ s_2 = 0.2157 \ Btu/lb.^0R$

Given that the power input to the compressor is 2 hp;

Then converting to Btu/hr ;we known that since 1 hp = 2544.4342 Btu/hr

2 hp = 2 × 2544.4342 Btu/hr

2 hp = 5088.8684 Btu/hr

The steady state energy for a compressor can be expressed by the formula:

$0 = Q_c -W_c+m((h_1-h_e) + \dfrac{v_i^2-v_e^2}{2}+g(\bar \omega_i - \bar \omega_e)$

By neglecting kinetic and potential energy effects; we have:

$0 = Q_c -W_c+m(h_1-h_2) \\ \\ Q_c = -W_c+m(h_2-h_1)$

$Q_c = -5088.8684 \ Btu/hr +200 \ lb/hr( 115.91 -109.12) Btu/lb \\ \\$

$\mathbf{Q_c = -3730.8684 \ Btu/hr}$

b) To determine the entropy generation; we employ the formula:

$\dfrac{dS}{dt} =\dfrac{Qc}{T}+ m( s_1 -s_2) + \sigma _c$

In a steady state condition $\dfrac{dS}{dt} =0$

Hence;

$0=\dfrac{Qc}{T}+ m( s_1 -s_2) + \sigma _c$

$\sigma _c = m( s_1 -s_2) - \dfrac{Qc}{T}$

$\sigma _c = [200 \ lb/hr (0.2157 -0.2315) \ Btu/lb .^0R - \dfrac{(-3730.8684 \ Btu/hr)}{(40^0 + 459.67^0)^0R}]$

$\sigma _c = [(-3.16 ) \ Btu/hr .^0R + (7.4667 ) Btu/hr ^0R}]$

$\mathbf{\sigma _c = 4.3067 \ Btu/hr ^0R}$

5 0

4 years ago

Legal metrology would protect consumers from businesses that do not take measurements according to defined measuring regulations

sergij07 [2.7K]

From what my research concluded, true

5 0

4 years ago

A photovoltaic panel of dimension 2mÃ—4m is installed on the

blsea [12.9K]

Answer:

Explanation:

Simply put, a solar panel works by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity. Solar panels actually comprise many, smaller units called photovoltaic cells. (Photovoltaic simply means they convert sunlight into electricity. The attached diagram give an ilustsration of the photovotaic pannel mounted on a roof top.

Solution

To Determine the electric power generated for

a) A still summer day.

E = A * r * H * PR

E = Total Amount of Energy in kilowatt

A = Total Surface Area

r = efficiency Rating

H = global radiation value

PR = Performance Ratio

kwh = watt * Time/1000

kwh = 100 * 35/1000

3.5

b)

kwh = watt * Time/1000

kwh = 30 *15/1000

4.5

6 0

3 years ago