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4 years ago

State whether the following statements are true or false. Provide a brief justification for your answer.

Engineering

1 answer:

Lena [83]4 years ago

5 0

Answer:

[a] False.

[b]. True

[c]. false.

[d]. true.

[e]. true.

Explanation:

NB: SDOF simply means Simple Degree Of Freedom, that is to say it is a system that can be solved by differential equation such as the second order and the single differential equation.

So, the question asked us to determine if each of the scenario is true or false.

a. Consider a SDOF system with Coulomb damping. When displaced from the equilibrium position and released, the mass may not move at all.

ANSWER: FALSE.

REASON: The mass moved a little bit When displaced from the equilibrium position and released.

b. Consider a SDOF system with an ideal viscous damper. When displaced from the equilibrium position and released, the mass will always undergo oscillatory motion.

ANSWER: TRUE

REASON: for an ideal viscous damper. When displaced from the equilibrium position and released, the mass will always undergo oscillatory motion.

c. The damped natural frequency of a system is always greater than the undamped natural frequency

ANSWER: FALSE

REASON: The damped natural frequency of a system is always greater than the undamped natural frequency

d. For an undamped system undergoing a harmonic forcing, the amplitude of the response approaches zero as the forcing frequency becomes very high.

ANSWER: TRUE

REASON: the amplitude of the response approaches zero as the forcing frequency becomes very high for undamped system undergoing a harmonic forcing

e. The amplitude of free response of SDOF system with Coulomb damping decreases

ANSWER: TRUE

REASON: amplitude of free response of SDOF system with Coulomb damping decreases

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Paragraph summary on airplane history

irga5000 [103]

Answer:The Wright brothers invented and flew the first airplane in 1903, recognized as "the first sustained and controlled heavier-than-air powered flight". ... Airplanes had a presence in all the major battles of World War II. The first jet aircraft was the German Heinkel He 178 in 1939.

Explanation:

4 0

3 years ago

Suppose we use radix sort to sort the English-language strings below using standard lexicographic ordering (i.e. sort in alphabe

nlexa [21]

Answer:

a) 4 passes are required to sort the string.

b) 4

c) i) TARP

ii) CHIP

iii) PART

iv) TARP

v) TARP

d) O(k+n), n is no. of strings, k is largest no. of character in among the string

O(d*(n+10)), n is no. of integers

Explanation:

7 0

4 years ago

A rectangular car-top carrier of 1.7-ft height, 5.0-ft length (front to back), and 4.2-ft width is attached to the top of a car.

Nataliya [291]

Answer:

$\Delta P =1.2 \frac{1.3}{2}(26.822m/s)^2 (4.2*1.7*(0.3048)^2)=13.88 hp$

Explanation:

We can assume that the general formula for the drag force is given by:

$D= C_D \frac{\rho}{2}V^2 A$

And we can see that is proportional to the area. On this case we can calculate the area with the product of the width and the height. And we can express the grad force like this:

$D_1 = C_{D1} \frac{\rho}{2}V^2 (wh)$

Where w is the width and h the height.

The last formula is without consider the area of the carrier, but if we use the area for the carrier we got:

$D_2 = C_{D2} \frac{\rho}{2}V^2 (wh+ A_{carrier})$

If we want to find the additional power added with the carrier we just need to take the difference between the multiplication of drag force by the velocity (assuming equal velocities for both cases) of the two cases, and we got:

$\Delta P = C_{D2} \frac{\rho}{2}V^2 (wh+ A_{carrier}) V- C_{D1} \frac{\rho}{2}V^2 (wh) V$

We can assume the same drag coeeficient $C_{D1}=C_{D2}=C_{D}$ and we got:

$\Delta P = C_{D} \frac{\rho}{2}V^2 (wh+ A_{carrier}) V- C_{D} \frac{\rho}{2}V^2 (wh) V$

$\Delta P = C_{D} \frac{\rho}{2}V^3 (A_{carrier})$

1.7 ft =0.518 m

60 mph = 26.822 m/s

In order to find the drag coeffcient we ned to estimate the Reynolds number first like this:

$R_E= \frac{Vl}{v}= \frac{26.822m/s*0.518 m}{1.58x10^{-4} Pa s}= 8.79 x10^{4}$

And the value for the kinematic vicosity was obtained from the table of physical properties of the air under standard conditions.

Now we can find the aspect ratio like this:

$\frac{l}{h}=\frac{5}{1.7}2.941$

And we can estimate the calue of $C_D = 1.2$ from a figure.

And we can calculate the power difference like this:

$\Delta P =1.2 \frac{1.3}{2}(26.822m/s)^2 (4.2*1.7*(0.3048)^2)=13.88 hp$

8 0

3 years ago

Show how to connect the two circuit building blocks from the previous problem to create a circuit that transforms a priority-enc

Pavel [41]

Answer:

When xo =0, Do= 0, not 1

Explanation:

Use 8×3 priority encoder and 3×8 decoder

8 0

3 years ago

An individual eats fish from a river contaminated with benzene. What concentrations of benzene in water (mg/L) would produce a l

avanturin [10]

This question is incomplete, the complete question is;

An individual eats fish from a river contaminated with benzene. What concentrations of benzene in water (mg/L) would produce a lifetime cancer risk of 10⁻⁶ to an individual who eats 2 meals of fish per week for 30 years if the BCF for benzene is 10⁺³?

Answer:

0.021 mg/L concentration of benzene in water would produce a lifetime cancer risk 10⁻⁶ to an individual who eats 2 meals of fish per week for 30 years if the BCF for benzene is 10⁺³

Explanation:

Chronic daily intake (CDI) =(C/W) (Intake rate/ lifetime) ( Exposure)

values from EPA Exposure Factors Table)

CDI = [ (5.2 L/d × C mg/L 0.054 kg/d) / 70 kg] [30/70] [350/365]

CDI = 1.65 × 10⁻³C

Now concentration of benzene; ( RISK) = CDI × pF

= 10⁻⁶ = [2.9× 10⁻² / (MG/kg-d)] ( 1.65 × 10⁻³C)

C = 0.021 mg/L

Therefore 0.021 mg/L concentration of benzene in water would produce a lifetime cancer risk 10⁻⁶

5 0

3 years ago