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3 years ago

For three control stations,there should be how many start buttons in parallel with the suxiliary contact

1 answer:

6 0

The three load contacts connected between the three-phase power line and the motor close to connect the motor to the line. The normally open auxiliary contact connected in parallel with the two Start buttons closes to maintain the circuit to M coil when the Start button is released.

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Do heavier cars really use more gasoline? Suppose a car is chosen at random. Let x be the weight of the car (in hundreds of poun

RoseWind [281]

Answer:

Do heavier cars really use more gasoline? Suppose a car is chosen at random. Let x be the weight of the car (in hundreds of pounds), and let y be the miles per gallon (mpg)

Explanation:

6 0

3 years ago

For a given set of input values, a NAND gate produces the opposite output as an OR gate with inverted inputs.A. True

Verdich [7]

Answer:

Explanation:

For a given set of input values, A NAND gate produces exactly the same values as an OR gate with inverted inputs.

The truth table for a NAND gate with 2 inputs is as follows:

0 0 1

0 1 1

1 0 1

1 1 0

The truth table for an OR gate, is as follows:

0 0 0

0 1 1

1 0 1

1 1 1

If we add two extra columns for inverted inputs, the truth table will be this one:

0 0 1 1 1

0 1 1 0 1

1 0 0 1 1

1 1 0 0 0

which is the same as for the NAND gate, not the opposite, so the statement is false.

This means that the right choice is B.

3 0

3 years ago

Define the terms (a) thermal conductivity, (b) heat capacity and (c) thermal diffusivity

IceJOKER [234]

Explanation:

(a)

The measure of material's ability to conduct thermal energy (heat) is known as thermal conductivity. For examples, metals have high thermal conductivity, it means that they are very efficient at conducting heat. The SI unit of heat capacity is W/m.K.

The expression for thermal conductivity is:

$q=-\kappa \bigtriangledown T$

Where,

q is the heat flux

$\kappa$ is the thermal conductivity

$\bigtriangledown T$ is the temperature gradient.

(b)

Heat capacity for a substance is defined as the ratio of the amount of energy required to change the temperature of the substance and the magnitude of temperature change. The SI unit of heat capacity is J/K.

The expression for Heat capacity is:

$C=\frac{E}{\Delta T}$

Where,

C is the Heat capacity

E is the energy absorbed/released

$\Delta T$ is the change in temperature

(c)

Thermal diffusivity is defined as the thermal conductivity divided by specific heat capacity at constant pressure and its density. The Si unit of thermal diffusivity is m²/s.

The expression for thermal diffusivity is:

$\alpha=\frac{\kappa}{C_p \times \rho}$