The true answer is the choice A
Scientists <span>can predict volcanic eruptions as long as adequate resources are available.Volcanic eruptions are one of the earthly activities which can be predicted by means of adequate resources (w</span><span>arming of the earth's crust, appearance of volcanic lava etc...). By contrast, earthquakes is a dangerous natural </span>disaster<span> that scientists cannot be predicted or mastering the time where it occurs.</span>
Answer:
The temperature of well water be 288.07 K
Explanation:
We have given Heat in house 
Work done W = 900 J
Efficiency is given by 
Efficiency is also given by 
, here 
is lower temperature and 
is higher temperature
So 
So the temperature of well water be 288.07 K
As a transformer generates ac current of different voltage when the switch is closed and the current flows in the primary coil which induces a magnetic field.
Answer: Option 2
<u>Explanation:</u>
A transformer is an electric device which can vary the potential differences or voltages of an alternating current. It's a simple device composed of an iron core, a primary and the secondary current conducting coil.
The primary coil is attached to the switch which provides ac current through potential difference. Now this current induces a magnetic field in the iron core. When the voltage of this ac current is varied, the magnetic field varies and starts inducing ac current of different voltage in the secondary coil.
Thus, an AC current of different voltage flows in the secondary coil that can be used in small electric devices. This is how a transformer works. There are two kinds of transformers- Step Up and Step Down. A step up transformer increases the potential difference whereas the step down does the opposite.
Answer:
2. B
3. A
4. C
5. B
6. A
Explanation:
2. Sound waves use vibrating molecules to move. With this being said, sound waves would travel best through dense materials, and would travel worst in empty materials, like space. Using this information, you can infer that B would be the answer because water is denser than air and water is the densest material on that list.
3. The speed of the wave is equal to the frequency times the wavelength. Since it has a wavelength of 100 meter and 20 Hertz, the speed would 2000 m/s
4. Like noted in question 2, sound waves travel best in dense materials. Rock is the densest material in that last.
5. By looking at the chart, you can see that the speed increases by 4 m/s when the temperature increases by 10. Using simple division, you could determine that the speed would go up by 2 m/s since the jump between 15 degrees and 20 degrees is 5, which is half of 10, making the speed half of 4.
6. The speed would decrease because, like stated above, sound travels best through dense materials. Since rock is denser than air, the speed would decrease as it leaves.
Answer:
A) 2.09
B) -62.09°
Explanation:
If D = A+B+C then C = D - A - B
Converting both A and B to rectangular coordinates, we get:
A = [-4.07 , 4.68] and B = [6.19 , 3.87]
Replacing these values we can get the x and y components of C:
C = [0.98 , -1.85]
Its module is:
Its angle is:
