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Alenkasestr [34]
3 years ago
6

​For the "determine data needs" activity of a project, the optimistic estimated duration is 10 days, the pessimistic estimated d

uration is 20 days, the most likely time is 15 days. What is the expected duration of completing this activity?
Physics
1 answer:
Katena32 [7]3 years ago
5 0

Answer:

This is a PERT  (Program Evaluation and Review Technique) question and the expected duration of completing this activity can be solved using the formula below.

 Pert Expected Duration Estimate = ║Optimistic Duration + (4 x Most Likely Duration) + Pessimistic Duration║/6.

15 days = Most likely Activity Duration.

10 days = Optimistic Activity Duration

20 days = Pessimistic Activity Duration

Substituting these values, we will have

(10 +(4 X 15) +20)/6. The pert estimate is therefore calculated as 15 days

The expected duration of completing this activity = 15 days.

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A string of length L, fixed at both ends, is capable of vibrating at 309 Hz in its first harmonic. However, when a finger is pla
Scorpion4ik [409]

Answer:

 i = 0.3326 L

Explanation:

A fixed string at both ends presents a phenomenon of standing waves, two waves with the same frequency that are added together. The expression to describe these waves is

    2 L = n λ           n = 1, 2, 3…

The first harmonic or leather for n = 1

Wave speed is related to wavelength and frequency

     v = λ f

     λ = v / f

Let's replace in the first equation

    2 L = 1 (v / f₁)

For the shortest length L = L-l

   2 (L- l) = 1 (v / f₂)

These two equations form our equation system, let's eliminate v

    v = 2L f₁

    v = 2 (L-l) f₂

    2L f₁ = 2 (L-l) f₂

    L- l = L f₁ / f₂

    l = L - L f₁ / f₂

    l = L (1- f₁ / f₂)

.

Let's calculate

    l / L = (1- 309/463)

    i / L = 0.3326

4 0
3 years ago
The difference between the Carbon 12 and Carbon 14 isotopes is the
Elina [12.6K]
Answer:
The number of neutrons.

Explaination:
The atoms of carbon 12 contain 6 neutrons while the atoms of carbon 14 contain 8 neutrons
4 0
3 years ago
A proton (mass m = 1.67 × 10-27 kg) is being accelerated along a straight line at 2.50 × 1012 m/s2 in a machine. If the proton h
Veronika [31]

Answer:

(A) Speed will be 44.18\times 10^4m/sec

(b) Change in kinetic energy = 1560\times 10^{-19}      

Explanation:

We have given mass of proton m=1.67\times 10^{-27}kg

Acceleration of the proton a=2.50\times 10^{12}m/sec^2

Initial velocity u = 1.60\times 10^4 m/sec

Distance traveled by proton s = 3.90 cm = 0.039 m

(a) From third equation of motion we know that

v^2=u^2+2as

v^2=(1.60\times 10^4)^2+2\times 2.5\times 10^{12}\times 0.039

v=44.18\times 10^4m/sec

(b) Initial kinetic energy KE_I=\frac{1}{2}mv^2=\frac{1}{2}\times 1.67\times 10^{-27}\times (1.6\times 10^4)^2

Final kinetic energy KE_F=\frac{1}{2}mv^2=\frac{1}{2}\times 1.67\times 10^{-27}\times (44.18\times 10^4)^2

So change in kinetic energy \Delta KE=KE_F-KE_I=\frac{1}{2}\times 1.6\times 10^{-27}\times 10^8\times (44.18^2-1.6^2)=1560\times 10^{-19}J

6 0
3 years ago
Which statement best describes how work and power are different? a. To find work we need to know force and distance; to find pow
weqwewe [10]
A. To find work we need to know F and S; to find power we need to know F and V
6 0
3 years ago
The metal cases of electrical appliances are connected to an earth wire.Which statement is not correct?A The live wire may becom
labwork [276]

Given that metal cases of electrical appliances are connected to the wire, let's select the statement which is not correct from the list of statements.

The earth wire is used to protect you and help reduce the risk of receiving an electric shock. The earth wire reduces the risk of electric shock by creating a path for a fault or lose current to flow to the Earth.

The Live wire may become loose and touch the metal case. In this case, the earth wire will channel the fault current to the earth thereby reducing the risk of electric shock.

If the metal case becomes live, the earth wire conducts current to the ground. This helps prevent electric shock from the metal case.

The Earth wire has low or no resistance. It is always made of copper.

It provides a low resistance path to the ground.

Therefore, the statement ''the earth wire needs to have high resistance'' is NOT current.

ANSWER:

C. The earth wire needs to have a high reistance.

7 0
1 year ago
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