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babymother [125]

3 years ago

5

Humpback whales are known to produce a collection of elaborate and repeating sounds with frequencies starting at 20 Hz. The soun

d waves travel through water at speeds of approximately 1400 m/s. Determine the wavelengths of the waves at the for this starting frequency.

1 answer:

jasenka [17]3 years ago

8 0

Answer:

70 m.

Explanation:

Given,

Frequency, f = 20 HZ

speed of sound, v = 1400 m/s

wavelength of the waves = ?

we know,

v = f λ

$\lambda= \dfrac{v}{f}$

$\lambda= \dfrac{1400}{20}$

$\lambda=70\ m$

Hence, the wavelength of the wave is equal to 70 m.

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If a ball is thrown straight up into the air with an initial velocity of 65 ft/s, its height in feet after t seconds is given by

fgiga [73]

Answer:

a) $v_{1}=\frac{(62.5-66)ft}{(2.5-2)s}=-7ft/s$

$v_{2}=\frac{(65.94-66)ft}{(2.1-2)s}=-0.6ft/s$

$v_{3}=\frac{(66.0084-66)ft}{(2.01-2)s}=0.84ft/s$

$v_{4}=\frac{(66.001-66)ft}{(2.001-2)s}=1ft/s$

b) $v=65-32(2)=1ft/s$

Explanation:

From the exercise we got the ball's equation of position:

$y=65t-16t^{2}$

a) To find the average velocity at the given time we need to use the following formula:

$v=\frac{y_{2}-y_{1} }{t_{2}-t_{1} }$

Being said that, we need to find the ball's position at t=2, t=2.5, t=2.1, t=2.01, t=2.001

$y_{t=2}=65(2)-16(2)^{2} =66ft$

$y_{t=2.5}=65(2.5)-16(2.5)^{2} =62.5ft$

$v_{1}=\frac{(62.5-66)ft}{(2.5-2)s}=-7ft/s$

--

$y_{t=2.1}=65(2.1)-16(2.1)^{2} =65.94ft$

$v_{2}=\frac{(65.94-66)ft}{(2.1-2)s}=-0.6ft/s$

--

$y_{t=2.01}=65(2.01)-16(2.01)^{2} =66.0084ft$

$v_{3}=\frac{(66.0084-66)ft}{(2.01-2)s}=0.84ft/s$

--

$y_{t=2.001}=65(2.001)-16(2.001)^{2} =66.001ft$

$v_{4}=\frac{(66.001-66)ft}{(2.001-2)s}=1ft/s$

b) To find the instantaneous velocity we need to derivate the equation

$v=\frac{df}{dt}=65-32t$

$v=65-32(2)=1ft/s$

7 0

3 years ago

Light will not pass through a pair of polaroids when their axes are

Advocard [28]

Answer:

perpendicular

Explanation:

Polaroids are the material that is used to polarize the ray of light. Polaroid consists of microcrystals of herapathite.

When unpolarized light is passed through the Polaroid then ray appears to be of half the intensity and vibration of the ray in the single plane so, the emerged light is known as polarized light

Polaroids are used in the glasses to protect the eye from unwanted rays.

When Light does not pass through a pair of Polaroids then the axis of Polaroids will be perpendicular to the axis of ray.

8 0

3 years ago

A substance has life of 40 years. In how many years will the substance disintegrate to 1/8 of its initial size

tia_tia [17]

Answer:

5 years

Explanation:

$\frac{1}{8}(40)\\\\= 5$

8 0

2 years ago

How are changes in energy and matter related

Svetlanka [38]

Answer:

According to Einstein's famous equation, matter can convert into energy (and viceversa) as follows:

$E=mc^2$

where

E is the energy

m is the mass

c is the speed of light ( $3\cdot 10^8 m/s$ )

Given the huge value of $c^2$ , we see that even a tiny amount of matter is able to release a huge amount of energy, when the whole mass is converted into energy. This is precisely what happens in nuclear reactions. For example, in the process of nuclear fusion (that occurs in the core of the stars), two light nuclei fuse together into a heavier nucleus. The mass of the final nucleus is lower than the total mass of the initial nuclei, so part of the mass has been converted into energy according to the equation above: this is why the amount of energy produced by stars is so big.

5 0

3 years ago

100 POINTS.<br> PLEASE EXPLAIN YOUR ANSWER.

Drupady [299]

Explanation:

Draw free body diagrams for each mass.

There are 3 forces on the disk: weight force mg pulling down, normal force N pushing up, and tension force T pulling right.

There are 2 forces on the cylinder: tension force T pulling up and weight force 3mg pulling down.

Sum of forces on the disk in the centripetal direction:

∑F = ma

T = m v²/r

Sum of forces on the cylinder in the vertical direction:

∑F = ma

T − 3mg = 0

T = 3mg

Substituting:

3mg = m v²/r

3gr = v²

v = √(3gr)

Plug in values:

v = √(3 × 10 m/s² × 0.800 m)

v = √24 m/s

v ≈ 4.90 m/s

6 0

3 years ago