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guajiro [1.7K]
2 years ago
8

The iron-blade plow allowed humans to increase food production during what age?

Engineering
1 answer:
lilavasa [31]2 years ago
4 0

Answer:

The Iron Age

Explanation:

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Why is concrete on its own not a good material to use
Inga [223]

Answer:

It has poor tensile strength despite having high compressive strength

Explanation:

Concrete exhibits high compressive strength when used. However, it has very low compressive strength. This is the reason why concrete is normally combined with steel to make a composite building material called reinforced concrete. The steel reinforces concrete hence increasing the tensile strength in RC buildings. The end composite is durable and fireproof. Generally, the main reason why concrete is not use on its own is due to its poor tensile strength.

7 0
2 years ago
A tank with some water in it begins to drain. The function v ( t ) = 46 − 3.5 t determines the volume of the water in the tank (
olchik [2.2K]

Answer with Explanation:

Part a)

The volume of water in the tank as a function of time is plotted in the below attached figure.

The vertical intercept of the graph is 46.

Part b)

The vertical intercept represents the volume of water that is initially present in the tank before draining begins.

Part c)

To find the time required to completely drain the tank we calculate the volume of the water in the tank to zero.

0=46-3.5t\\\\3.5=46\\\\\therefore t=\frac{46}{3.5}=13.143minutes

Part d)

The horizontal intercept represents the time it takes to empty the tank which as calculated above is 13.143 minutes.

7 0
3 years ago
Lydia is the CEO for a large pharmaceutical manufacturer. Her company is in the final stages of FDA
weqwewe [10]
OSHA inspections are generally unannounced. In fact, except in four exceptional circumstances when advance notice may be given.


It is a criminal offense for any person to give unauthorized advance notice of an OSHA inspection.
5 0
3 years ago
An ideal Otto cycle has a compression ratio of 9.2 and uses air as the working fluid. At the beginning of the compression proces
Allushta [10]

Answer:

(a) The amount of heat transferred to the air, q_{out} is 215.5077 kJ/kg

(b) The net work output, W_{net}, is 308.07 kJ/kg

(c) The thermal efficiency is 58.8%

(d) The Mean Effective Pressure, MEP, is 393.209 kPa

Explanation:

(a) The assumptions made are;

c_p = 1.005 kJ/(kg·K), c_v = 0.718 kJ/(kg·K), R = 0.287 kJ/(kg·K),

Process 1 to 2 is isentropic compression, therefore;

T_{2}= T_{1}\left (\dfrac{v_{1}}{v_{2}}  \right )^{k-1} = 300.15\times 9.2^{0.4} = 729.21 \, K

From;

\dfrac{p_{1}\times v_{1}}{T_{1}} = \dfrac{p_{2}\times v_{2}}{T_{2} }

We have;

p_{2} = \dfrac{p_{1}\times v_{1}\times T_{2}}{T_{1} \times v_{2}} = \dfrac{98\times 9.2\times 729.21}{300.15 } = 2190.43 \, kPa

Process 2 to 3 is reversible constant volume heating, therefore;

\dfrac{p_3}{T_3} =\dfrac{p_2}{T_2}

p₃ = 2 × p₂ = 2 × 2190.43 = 4380.86 kPa

T_3 = \dfrac{p_3 \times T_2}{p_2} =\dfrac{4380.86  \times 729.21}{2190.43} = 1458.42 \, K

Process 3 to 4 is isentropic expansion, therefore;

T_{3}= T_{4}\left (\dfrac{v_{4}}{v_{3}}  \right )^{k-1}

1458.42= T_{4} \times \left (9.2 \right )^{0.4}

T_4 = \dfrac{1458.42}{(9.2)^{0.4}}  = 600.3 \, K

q_{out} = m \times c_v \times (T_4 - T_1) = 0.718  \times (600.3 - 300.15) = 215.5077 \, kJ/kg

The amount of heat transferred to the air, q_{out} = 215.5077 kJ/kg

(b) The net work output, W_{net}, is found as follows;

W_{net} = q_{in} - q_{out}

q_{in} = m \times c_v \times (T_3 - T_2) = 0.718  \times (1458.42 - 729.21) = 523.574 \, kJ/kg

\therefore W_{net} = 523.574 - 215.5077 = 308.07 \, kJ/kg

(c) The thermal efficiency is given by the relation;

\eta_{th} = \dfrac{W_{net}}{q_{in}} \times 100=  \dfrac{308.07}{523.574} \times 100= 58.8\%

(d) From the general gas equation, we have;

V_{1} = \dfrac{m\times R\times T_{1}}{p_{1}} = \dfrac{1\times 0.287\times 300.15}{98} =0.897\, m^{3}/kg

The Mean Effective Pressure, MEP, is given as follows;

MEP =\dfrac{W_{net}}{V_1 - V_2} = \dfrac{W_{net}}{V_1 \times (1- 1/r)}= \dfrac{308.07}{0.897\times (1- 1/9.2)} = 393.209 \, kPa

The Mean Effective Pressure, MEP = 393.209 kPa.

3 0
3 years ago
Need help fast I been stuck in this for the longest
gavmur [86]

Answer:

3rd and 4rth

Explanation:

a geologist studies the earth and both of these have something to do with the earth

6 0
3 years ago
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