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3 years ago

Why machines are never 100 percent efficient

2 answers:

8 0

Machines are never 100% efficient because they are made by humans and we make errors and nothing we make is perfect, that's why the machines we build are not 100% accurate or efficient.

algol133 years ago

4 0

The efficiency of an actual machine is never 100% because of the Second law of thermodynamics which states that the quality of energy will decay, eventually becoming heat. This means that some of the work put into the system is transformed (lost) into thermal energy(heat) therefore, causing the percent to reduce.

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A kid on a playground swing makes a complete to-and-fro swing each 2 seconds.

sashaice [31]

Answer:

The frequency of the swing: 1/2 Hertz

The period is: 2 Seconds

Explanation:

The time the kid takes to make a complete to-and-fro swing = 2 seconds

The period, T, is the time it takes to make one complete cycle of an oscillatory motion, therefore, we have;

The frequency, f, is the number of cycles completed each second, therefore, we have;

The time for 1 cycle = 2 seconds

2 seconds = 1 cycle

Dividing both sides by 2 gives;

2/2 seconds = 1/2 cycles

2/2 = 1

In 2/2 = 1 seconds The number of cycles completed = 1/2 cycles

Therefore, the number of cycles completed per (one) second = 1/2 cycles

Therefore the frequency of the swing, f = 1/2 cycle/seconds = 1/2 Hertz

The period, T, is the time it takes to complete one to-and-fro swing which is one cycle which is 2 seconds

Therefore, the period is 2 Seconds.

4 0

3 years ago

What effort force will be required to lift the 20 N object using the pulley above?

Umnica [9.8K]

Answer:

I think it is 5N.

Explanation:

4 0

3 years ago

Two objects, Object A and Object B, need to be identified. Object A's index of refraction is determined to be 1.77, and Object B

Slav-nsk [51]

The correct answer is

C. Light can pass through Object B faster than it can pass through Object A.

In fact, the index of refraction of a material is defined as:

$n=\frac{c}{v}$

where c is the speed of light in vacuum and v is the speed of light in the material. Rearranging the equation, we can write the speed of light in the material as:

$v=\frac{c}{n}$

So we that, the smaller the refractive index n, the greater the speed of light in the material, v. In this problem, object B has lower refractive index than object A, so light travels faster in object B.

4 0

4 years ago

Read 2 more answers

A slinky is stretched by two forces. When the forces are removed, the slinky returns to its original length. The slinky has been

e-lub [12.9K]

Answer: elastically deformed or non-permanently deformed

Explanation:

According to classical mechanics, there are two types of deformations:

-Plastic deformation (also called irreversible or permanent deformation), in which the material does not return to its original form after removing the applied force, therefore it is said that the material was permanently deformed.

This is because the material undergoes irreversible thermodynamic changes while it is subjected to the applied forces.

-Elastic deformation (also called reversible or non-permanent deformation), in which the material returns to its original shape after removing the applied force that caused the deformation.

In this case the material also undergoes thermodynamic changes, but these are reversible, causing an increase in its internal energy by transforming it into elastic potential energy.

Therefore, the situation described in the question is related to elastic deformation.

8 0

3 years ago

How should the student change the circuit to give negative values for current and

natulia [17]

Answer:

changing the polarity or direction of the battery changes the sign of the voltage and the current

Explanation:

The sign of current and voltage are due to established conventions.

The way that a DC circuit with negative current values is by changing the polarity of the power source or by inverting the battery, this creates that the electrons move in the opposite direction

Changing the battery also changes the direction of the power difference, since the potential from positive to negative, in most cases negative is assigned a potential of zero volts

In summary, changing the polarity or direction of the battery changes the sign of the voltage and the current

3 0

3 years ago