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2 years ago

12

As water begins to boil in a kettle the hotter water at the bottom of the kettle closest to the stove begins to rise and the coo

ler water above sinks and warms. Why does this occur?

1 answer:

Vika [28.1K]2 years ago

4 0

This occurs due to convection! warm air (and water) rises and the cold sinks!

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What will happen if our atmosphere was oxygen

qaws [65]

Most humans would die do to the excess oxyegen

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3 years ago

If a photon has a frequency of 1.15 × 1015 hertz, what is the energy of the photon? Given: Planck's constant is 6.63 × 10-34 jou

Vika [28.1K]

<span>5.82 x 10-49 joules7.62 x 10-19 joules8.77 x 10-12 joules1.09 x 10-12<span> joules </span><span>answer is b</span></span>

8 0

3 years ago

Read 2 more answers

Experiments using "optical tweezers" measure the elasticity of individual DNA molecules. For small enough changes in length, the

GalinKa [24]

Answer:

Spring constant, k = 0.3 N/m

Explanation:

It is given that,

Force acting on DNA molecule, $F=1.5\ nN=1.5\times 10^{-9}\ N$

The molecule got stretched by 5 nm, $x=5\times 10^{-9}\ m$

Let k is the spring constant of that DNA molecule. It can be calculated using the Hooke's law. It says that the force acting on the spring is directly proportional to the distance as :

$F=-kx$

$k=\dfrac{F}{x}$

$k=\dfrac{1.5\times 10^{-9}\ N}{5\times 10^{-9}\ m}$

k = 0.3 N/m

So, the spring constant of the DNA molecule is 0.3 N/m. Hence, this is the required solution.

8 0

3 years ago

An open pipe of length 0.58 m vibrates in the third harmonic with a frequency of 939Hz. What is the speed of sound through the a

vaieri [72.5K]

363 m/s is the speed of sound through the air in the pipe.

Answer: Option B

<u>Explanation:</u>

The formula used to calculate the wavelength given as below,

$Wavelength (\lambda)=\frac{\text { wave velocity }(v)}{\text { frequency }(f)}$

$v=\lambda \times f$ --------> eq. 1

In power system, harmonics define by positive integers of the fundamental frequency. So the third order harmonic is a multiple of the third fundamental frequency. Each harmonic creates an additional node and an opposite node, as well as an additional half wave within the string.

If the number of waves in the circuit is known, the comparison between standing wavelength and circuit length can be calculated algebraically. The general expression for this given as,

$L=\frac{n \lambda}{2}$

For first harmonic, n =1

$L=\frac{\lambda}{2}$

For second harmonic, n =2

$L=\frac{2 \lambda}{2}=\lambda$

For third harmonic, n =3

$L=\frac{3 \lambda}{2}$

$\lambda=\frac{2 L}{3}$ -------> eq. 2

Here given f = 939 Hz, L = 0.58 m...And, substitute eq 2 in eq 1 and values, we get

$v=\frac{2 \times 0.58 \times 989}{3}=\frac{1089.24}{3}=363.08 \mathrm{m} / \mathrm{s}$

3 0

3 years ago

An electric motor has an effective resistance of 29. 4 ω and an inductive reactance of 42. 6 ω. When working under load. the rms

Readme [11.4K]

An electric motor has an effective resistance of 29. 4 ω and an inductive reactance of 42. 6 ω. When working under load. the rms voltage across the alternating source is 442 v. The rms current will be 8.54 A

AC stands for “Alternating Current,” meaning voltage or current that changes polarity or direction, respectively, over time. AC electromechanical generators, known as alternators, are of simpler construction than DC electromechanical generators.

RMS or root mean square current/voltage of the alternating current/voltage represents the D.C current/voltage that dissipates the same amount of power as the average power dissipated by the alternating current/voltage. For sinusoidal oscillations, the RMS value equals peak value divided by the square root of 2.

I (RMS) = RMS voltage / $\sqrt{R^{2}+ X_{L} { ^{2} }$

= 442 / $\sqrt{29.4^{2} + 42.6^{2} }$

= 442 / $\sqrt{864.36 + 1814.76}$

= 442 / $\sqrt{2679.12}$

= 8.54 A

To learn more about Alternating Current here

brainly.com/question/11673552

#SPJ4

6 0

1 year ago