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3 years ago

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A 15.0-kg block is dragged over a rough, horizontal surface by a 75-n force acting at 21° above the horizontal. the block is dis

placed 5.7 m, and the coefficient of kinetic friction is 0.200. (a) find the work done on the block by the 75-n force.

1 answer:

Zepler [3.9K]3 years ago

6 0

Some dogs may inherit a susceptibility to epilepsy.

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Although it shouldn’t have happened, on a dive I fail to watch my SPG and run out of air. If my buddy is close by, my best optio

Airida [17]

Answer:

A) ascend using my buddy's alternate air source / make a controlled emergency swimming ascent

Explanation:

When it is found that you are out of air while under water, first of all don't panic, look for your buddy. If you are unable to do that so, then you need to make an emergency ascent. First try to make a <u>Controlled Emergency Swimming Ascent</u> (CESA). This ascent remains under control and is performed at a safe ascent rate. As you ascend the air in your lungs will expand with decreasing ambient pressure. To avoid an over pressurization injury, always exhale a continuous string of bubbles while going up.

If you are not sure you will make to the surface that leading to inhale the only option is to turn the CESA into a Buoyant Emergency Ascent. To be ready locate your weight system as you ascend. As an addition remove the weight from one of weight pockets and hold it away from your body in preparation of dropping if necessary. Dropping the weight will give you an upward buoyant force which is an <u>uncontrolled buoyant emergency ascent</u> and <u><em>should be performed only as the last option</em></u>.

So, according to this, first, always have a look at your SPG. Then, if you are out of air, look for your buddy, if not found then make CESA and the last option will be buoyant emergency ascent.

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3 years ago

A woman jogs 20 km in 4 hours, then another 10 km in 2 hours. What is her average speed?

murzikaleks [220]

Answer:

I think 5 km/h but I am not sure

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3 years ago

What is the energy of a photon that has the same wavelength as an electron having a kinetic energy of 15 ev?

serg [7]

Answer: $6.268(10)^{-16}J$

Explanation:

The kinetic energy of an electron $K_{e}$ is given by the following equation:

$K_{e}=\frac{(p_{e})^{2} }{2m_{e}}$ (1)

Where:

$K_{e}=15eV=2.403^{-18}J=2.403^{-18}\frac{kgm^{2}}{s^{2}}$

$p_{e}$ is the momentum of the electron

$m_{e}=9.11(10)^{-31}kg$ is the mass of the electron

From (1) we can find $p_{e}$ :

$p_{e}=\sqrt{2K_{e}m_{e}}$ (2)

$p_{e}=\sqrt{2(2.403^{-18}J)(9.11(10)^{-31}kg)}$

$p_{e}=2.091(10)^{-24}\frac{kgm}{s}$ (3)

Now, in order to find the wavelength of the electron $\lambda_{e}$ with this given kinetic energy (hence momentum), we will use the De Broglie wavelength equation:

$\lambda_{e}=\frac{h}{p_{e}}$ (4)

Where:

$h=6.626(10)^{-34}J.s=6.626(10)^{-34}\frac{m^{2}kg}{s}$ is the Planck constant

So, we will use the value of $p_{e}$ found in (3) for equation (4):

$\lambda_{e}=\frac{6.626(10)^{-34}J.s}{2.091(10)^{-24}\frac{kgm}{s}}$

$\lambda_{e}=3.168(10)^{-10}m$ (5)

We are told the wavelength of the photon $\lambda_{p}$ is the same as the wavelength of the electron:

$\lambda_{e}=\lambda_{p}=3.168(10)^{-10}m$ (6)

Therefore we will use this wavelength to find the energy of the photon $E_{p}$ using the following equation:

$E_{p}=\frac{hc}{lambda_{p}}$ (7)

Where $c=3(10)^{8}m/s$ is the spped of light in vacuum

$E_{p}=\frac{(6.626(10)^{-34}J.s)(3(10)^{8}m/s)}{3.168(10)^{-10}m}$

Finally:

$E_{p}=6.268(10)^{-16}J$

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3 years ago

B) Smartphone, iPad, and tablet are also a kind of computer.

valentinak56 [21]

Answer:

Yes

Explanation:

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3 years ago

Water on a smooth floor can made you slip, which means water is also a lubricant. Can you think of reasons why oil and grease an

DiKsa [7]

Answer:Water is easily evaporated, and oil and grease will not evaporate.

Explanation:

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3 years ago