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3 years ago

7

A special device can transmit sound that is out of phase with the sound of a noisy jackhammer to the jackhammer operator by mean

s of earphones. Over the noise of the jackhammer, the operator can easily hear your voice, while you are unable to hear his. Explain.

1 answer:

goldenfox [79]3 years ago

4 0

Answer:

, l l. l

Explanation:

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When changing a tire sized 195/75 R15 to a 5 percent lower profile, the correct tire size would be _____

valentinak56 [21]

Answer and explanation:

When you are changing a car tire, the most important thing is to keep the total diameter as equal as possible.

The total car tire diameter can be calculated as:

$D_{tot orig}=\frac{195 \cdot 75}{2540 \cdot 2}+15''=26.5''$

The profile of this tire is 75 (the higher/taller relation), therefore a 5 percent lower profile would be:

pr=0.95·75=71.25

The problem is that the profiles are normalized and the nearest profile available is 70.

If we take a theorical tire with a profile of 71.25:

$D_{tot orig}=D_{new}\\\frac{195 \cdot 75}{2540 \cdot 2}+15''=\frac{X \cdot 71.25}{2540 \cdot 2}+15''\\X=205.26$

The theorical tire size should be 205/71 R15.

If we look for a real tire size, we should look for a tire with a diameter nearest to 26.5'' and a profile of 70.

The best option for real tire size is: Tire 225/70 R14 (wheel diameter of 26.4'') or 205/70 R15 (wheel diameter of 26.3'').

3 0

4 years ago

Which of the following is a benefit of physical activity?

zaharov [31]

Answer:

B

Explanation:

better concentration

5 0

3 years ago

Read 2 more answers

When a 100-N force acts horizontally on an 8.0-kg chair, the chair moves at a constant speed across the level floor. Which state

TiliK225 [7]

Answer:

The applied force is greater than the frictional force.

Explanation:

the chair moves at <u>a constant speed</u><u> </u><u>therefore</u><u>,</u><u> </u><u>the</u><u> </u><u>answer</u><u> </u><u>is</u><u> </u><u>not</u><u> </u><u>A</u><u> </u><u>or</u><u> </u><u>C</u><u>.</u>

if there is no friction then the chair <u>would accelerate and it would not be at a constant speed</u><u>.</u>

hence, the only possible answer is B.

7 0

3 years ago

You are taking a picture of a giraffe that is standing far away from you. The image is just too small, so you swap the 60-mm-foc

vfiekz [6]

Explanation:

Given that, you are taking a picture of a giraffe that is standing far away from you. The image is just too small, so you swap the 60-mm-focal-length lens in your camera for a 960 mm telephoto lens such that,

$m_1=960\ mm$

$m_2=60\ mm$

We need to find the the factor with which the size of the image increases. It can be calculated by taking ratios of both $m_1\ and\ m_2$

So, $\dfrac{m_1}{m_2}=\dfrac{960}{60}$

$\dfrac{m_1}{m_2}=16$

So, the size of image increases by a factor of 16. Hence, this is the required solution.

4 0

3 years ago

Richard is driving home to visit his parents. 150 mi of the trip are on the interstate highway where the speed limit is 65 mph .

Serggg [28]

Answer:

t = 25.5 min

Explanation:

To know how many minutes does Richard save, you first calculate the time that Richard takes with both velocities v1 = 65mph and v2 = 80mph.

$t_1=\frac{x}{v_1}=\frac{150mi}{65mph}=2.30h\\\\t_2=\frac{x}{v_2}=\frac{150mi}{80mph}=1.875h$

Next, you calculate the difference between both times t1 and t2:

$\Delta t=t_1-t_2=2.30h-1.875h=0.425h$

This is the time that Richard saves when he drives with a speed of 80mph. Finally, you convert the result to minutes:

$0.425h*\frac{60min}{1h}=25.5min=25\ min\ \ 30 s$

hence, Richard saves 25.5 min (25 min and 30 s) when he drives with a speed of 80mph

3 0

3 years ago