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kvv77 [185]
3 years ago
14

A certain heat engine takes in 300 J of energy from a hot source and then transfers 200 J of that energy to a colder object. Wha

t is the efficiency of the heat engine
Physics
1 answer:
Greeley [361]3 years ago
5 0

Answer:

The efficiency is 0.33, or 33%.

Explanation:

From the thermodynamics equations, we know that the formula for the efficiency of a heat engine is:

\eta=1-\frac{Q_2}{Q_1}

Where η is the efficiency of the engine, Q_1 is the heat energy taken from the hot source and Q_2 is the heat energy given to the cold object. So, plugging the given values in the formula, we obtain:

\eta=1-\frac{200J}{300J}=0.33

This means that the efficiency of the heat engine is 0.33, or 33% (The efficiency of an engine is dimensionless).

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he fan blades on a jet engine make one thousand revolutions in a time of 54.9 ms. What is the angular frequency of the blades?
Gnesinka [82]

So, the angular frequency of the blades approximately <u>36.43π rad/s</u>.

<h3>Introduction</h3>

Hi ! Here I will discuss about the angular frequency or what is also often called the angular velocity because it has the same unit dimensions. <u>Angular frequency occurs, when an object vibrates (either moving harmoniously / oscillating or moving in a circle)</u>. Angular frequency can be roughly interpreted as the magnitude of the change in angle (in units of rad) per unit time. So, based on this understanding, the angular frequency can be calculated using the equation :

\boxed{\sf{\bold{\omega = \frac{\theta}{t}}}}

With the following condition :

  • \sf{\omega} = angular frequency (rad/s)
  • \sf{\theta} = change of angle value (rad)
  • t = interval of the time (s)

<h3>Problem Solving</h3>

We know that :

  • \sf{\theta} = change of angle value = 1,000 revolution = 1,000 × 2π rad = 2,000π rad/s >> Remember 1 rev = 2π rad/s.
  • t = interval of the time = 54.9 s.

What was asked :

  • \sf{\omega} = angular frequency = ... rad/s

Step by step :

\sf{\omega = \frac{\theta}{t}}

\sf{\omega = \frac{2,000 \pi}{54.9}}

\boxed{\sf{\omega \approx 36.43 \pi \: rad/s}}

<h3>Conclusion :</h3>

So, the angular frequency of the blades approximately 36.43π rad/s.

8 0
2 years ago
Which best describes a value for density
scoray [572]
Density can be any number, as long as it has the right units.

A unit of density has to be (a unit of mass) divided by (a unit of volume).
The most common one is gram/cm^3.
8 0
3 years ago
A crowbar having the length of 1.75m is used to balance a load between the fulcrum and the load is 0.5m calculate MA
aliina [53]

Answer:

1.70

Explanation:

substract 1.75-0.5

3 0
2 years ago
A student pushes a 2.85 kg cart causing it to accelerate at a rate of 4.9 m/s squared .What amount of force must the student hav
uysha [10]
In order to find the force (F), you would have to use the formula for it:
F=ma
where m is mass and a is acceleration.
In the problem, the mass is 2.85kg and the acceleration is 4.9m/s^2.
Therefore,
F=2.85kg(4.9m/s^2)
F=13.965kg(m/s^2)
Since N=kg(m/s^2)
F=13.965N
And because the problem requires that we use only 2 significant figures,
F=13N
Therefore, the student must exert 13N of force.

7 0
3 years ago
I need help on ideas for a science project.. (highschool ideas)
Nana76 [90]

A research question that would complete the third question you need that are related to the first 2 questions which are:

  • “what type of masks help prevent fog on glasses when breathing?”
  • “does a mask’s material affect the level of fog on glasses as an effect of breathing?”

Would be: "Are there any available masks that could prevent fog on glasses that could be improved upon"?

This new research question would help you find out if there is an already existing mask that could be made better.

<h3>What is a Research Question?</h3>

This refers to "a question that a research project sets out to answer". and seeks to give answers to particular phenomena.

Hence, we can see that the new research question Would be: "Are there any available masks that could prevent fog on glasses that could be improved upon"?

This new research question would help you find out if there is an already existing mask that could be made better.

Read more about research questions here:

brainly.com/question/25257437

#SPJ1

8 0
1 year ago
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