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2 years ago

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You have designed a machine that requires 1000 J of work from a motor for every 800 J of useful work done by the machine. What i

s the efficiency of the machine?

1 answer:

valentinak56 [21]2 years ago

4 0

Answer:

80%

Explanation:

$efficiency = \frac{useful \: work \: done}{total \: energy \: input}$

800 / 1000 = 0.8

Efficiency = 0.8 *100 = 80%

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According to Ohm's law, a circuit with a high resistance _____. will have a low electric current will have a high electric curre

lyudmila [28]

Remark
When you are asked a question like this, the first thing to do is search out a formula and put some limits on it.

Formula
I = E/R which comes from E = IR. To get to the derived formula, divide both sides by R
E/R = I*R/R
E/R = I

Discussion
This is an inverse relationship. That means that as one goes up the other one will go down.

So in this case you keep E constant and you manipulate R and look at your results for I

Case 1
Let us say that E = 10 volts
Let us also say the R = 10 ohms

I = E/R
I = 10/10
I = 1 ohm

Case Two
Let's raise the Resistance to 100 ohms
E = 10
R = 100
I = 10/100 = 0.1

Conclusion
As the Resistance goes up, the current goes down. Answer: A

8 0

3 years ago

Read 2 more answers

Joe balances a stationary coin on the the tip of his finger 20 cm from the top of the table. How much work is Joe doing?

adell [148]

The work done by Joe is 0 J.

<u>Explanation</u>:

When a force is applied to an object, there will be a movement because of the applied force to a certain distance. This transfer of energy when a force is applied to an object that tends to move the object is known as work done.

The energy is transferred from one state to another and the stored energy is equal to the work done.

W = F . D

where F represents the force in newton,

D represents the distance or displacement of an object.

Force = 0 N, D = 20 cm = 0.20 m

W = 0 $\times$ 0.20 = 0 J.

Hence the work done by Joe is 0 J.

7 0

3 years ago

How fast is a wave traveling if it has a wavelength of 7 meters and a frequency of 11 Hz?

pashok25 [27]

Answer:

$\huge{ \boxed{ \bold{ \sf{77 \: m/s}}}}$

☯ Question :

How fast is a wave travelling if it has a wavelength of 7 meters and a frequency of 11 Hz?

☯ $\underbrace{ \sf{Required \: Answer : }}$

☥ Given :

Wavelength ( λ ) = 7 meters
Frequency ( f ) = 11 Hz

☥ To find :

Speed of sound ( v ) = ?

☄ We know ,

$\boxed{ \sf{v = f \times λ}}$

where ,

v = speed of sound
f = frequency
λ = wavelength

Now, substitute the values and solve for v.

➺ $\sf{v = 11 \times 7}$

➺ $\boxed{ \sf{v = 77 \: m/s}}$

-------------------------------------------------------------------

✑ Additional Info :

Frequency : The number of complete vibrations made by a particle of a body in one second is called it's frequency. It is denoted by the letter f . The SI unit of frequency is hertz ( Hz ).

Wavelength : The distance between two consecutive compressions or rarefactions of a sound wave is called wavelength of that wave. It is denoted by λ ( lambda ) and it's SI unit is m.

Speed of a sound wave : The distance covered by a sound wave in one second is called speed of sound wave. It depends on the product of wavelength and frequency of the wave.

Hope I helped!

Have a wonderful time! ツ

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7 0

3 years ago

What does the voltage-current graph above show about the relationship between voltage and current, and how do these properties a

zubka84 [21]

The answer is as voltage increases current increases and therefore resistance would remain constant

4 0

3 years ago

A new roller coaster contains a loop-the-loop in which the car and rider are completely upside down. If the radius of the loop i

Mila [183]

Answer:

11.4 m/s

Explanation:

The expression for the Centripetal acceleration is :

$a=\frac{v^2}{R}$

Where, a is the accleration

v is the velocity around circumference of circle

R is radius of circle

In the given question,

a = g = Acceleration due to gravity as the car is at top = $9.81\ m/s^2$

v = ?

R = 13.2 m

So,

$9.81=\frac{v^2}{13.2}$

$v^2=9.81\times {13.2}$

<u>v = 11.4 m/s</u>

8 0

3 years ago