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3 years ago

A steam engine absorbs 4 x 105 J and expels 3.5 x 105 J in each cycle. What is its efficiency?

1 answer:

3 0

Input heat, Qin = 4 x 10⁵ J
Output heat, Qout = 3.5 x 10⁵ J

From the first Law of thermodynamics, obtain useful work performed as
W = Qin - Qout
= 0.5 x 10⁵ J

By definition, the efficiency is
η = W/Qin
= 100*(0.5 x 10⁵/4 x 10⁵)
= 12.5%

Answer: The efficiency is 12.5%

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SVETLANKA909090 [29]

Answer: velocity

Explanation: Hope this helps :)

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3 years ago

Water is flowing at 4.0 m/s in a circular pipe. If the diameter of the pipe decreases to 1/2 of its former value, what is the ve

Montano1993 [528]

Answer:

v₂ = 16 m/s

Explanation:

We can use the continuity equation, which is as follows:

$A_1v_1 = A_2v_2\\$

where,

A₁ = Area of inlet = πd²/4

A₂ = Area of outlet = π(d/2)²/4 = πd²/16

v₁ = velocity at inlet = 4 m/s

v₂ = velocity at outlet = ?

Therefore,

$(\frac{\pi d^2}{4})(4\ m/s)=(\frac{\pi d^2}{16})v_2\\\\$

v₂ = 16 m/s

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3 years ago

Which of the following is not the one of the influencing factors when it comes to body type

serg [7]

Where are the answer choice ?

3 0

3 years ago

Read 2 more answers

a new car is advertised as having anti-noise technology. The manufacturer claims that inside the car any sound on negated. Evalu

nirvana33 [79]

Answer:

I guess you mean that any sound coming from outside is negated, first, this would mean that you can not hear some signals that may help you to avoid accidents, so you do not want this technology.

Now, let's see if it is possible.

Suppose you have a soundwave approaching the car, the car needs to cancel the soundwaves as the soundwaves approach to the surface, to do it, you need to create another wave that is equal in amplitude, but with a change of phase of pi.

in order to do this, the car must be able to "analyze" the coming soundwave and instantly create another one to cancel it. Suppose that the sound is canceled. now if the sound changes, the car must be able to also change the sound that the car is producing, this instantaneous change is one of the problems.

Another problem is that, as you know, the sound propagates as spherical waves, this means that the wavefront of a wave produced far away will have a bigger radius than the soundwave produced by the car, then we never will have a situation where the wavefront is canceled: This means that we only can cancellate the sound in some areas of the car, and we still will have some sound in other parts of the car.

Another way to isolate the car is with isolating panels, those panels absorb the sound and transmit a very little amount of it (those panels are used in recording studios, for example). With enough of those you can cancel almost all the sound coming from the outside, but to do this you will need a big car because the amount of isolating material needed is a lot.

We can conclude that the manufacturers claim is not correct.

5 0

3 years ago

What is the least value of an ammeter Is it 1. 0.1 2. 0.10 3. 0.2 4. 0.5

givi [52]

The least value varies depends on ammeter range. In the given question, ammeter range is not mentioned. So, the least value of an ammeter is 0.1 or 0.5 (depends on ammeter range).

Explanation:

The least value of an ammeter is the measure of the smallest number which can be observed in ammeter. So the least value will be varying depending upon its range. If we consider the range of ammeter is 30 A and the scale readings are 10 numbers, then the least value will be 30/10 = 3 A per scale.

So the least value is determined as $\frac{Range of ammeter}{No.of scales}$

So among the given options 0.1 is most suitable for an ammeter with range of 3 A with 30 divisions.

3 0

3 years ago