Why can’t you identify a substance on the basis of density alone?

1 answer:

8 0

Because density changes, it do depends on the state of the substance it's a state variable, for eg you have a cup of water at 4°c at this point the water possess the highest density, but at 0°c the density decreases, due to anamolous behaviour of water molecules by creating a cage mechanised structure.. (then according to your statement you might say both are different, but though they are same just difference in thier states) thus you can't have density alone as a basis

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3. The velocity of sound is 332 m/s. Answer the following questions:

Angelina_Jolie [31]

Answer:

20 Hz, 20000 Hz

0.0166 m, 16.6 m

Explanation:

The minimum frequency that a human ear can hear is 20 Hz

The maximum frequency that a human ear can hear is 20000 Hz.

v = Velocity of sound = 332 m/s

Wavelength is given by

$\lambda=\dfrac{v}{f}\\\Rightarrow \lambda=\dfrac{332}{20}\\\Rightarrow \lambda=16.6\ \text{m}$

The longest wavelength that can be heard by the human ear is 16.6 m

$\lambda=\dfrac{332}{20000}\\\Rightarrow \lambda=0.0166\ \text{m}$

The shortest wavelength that can be heard by the human ear is 0.0166 m.

3 0

2 years ago

How is energy conserved in a transformation?

irina [24]

As the water plunges, its velocity increases. Its potential energy becomes kineticenergy. The law of conservation of energy states that when one form of energy istransformed to another, no energy is destroyed in the process. ... So the total amount of energy is the same before and after any transformation.

hope it helps

5 0

3 years ago

FIGURE 1 shows part of a mass spectrometer. The whole arrangement is in a vacuum. Negative ions of mass 2.84 x 10-20 kg and char

yuradex [85]

Yes, the ions can exit slit P without being deflected, if the electric field strength is 170.6 N/C

Explanation:

When the ions are inside the container, they are subjected to two forces, with directions opposite to each other:

The force due to the electric field, whose magnitude is $F_E=qE$ , where q is the charge of the ion and E is the strength of the electric field
The force due to the magnetic field, whose magnitude is $F_B=qvB$ , where v is the speed of the ions and B is the strength of the magnetic field

The ions will move straight and undeflected if the two forces are equal and opposite. By using Fleming Left Hand rule, we notice that the magnetic force on the (negative) ions point upward: this means that the electric field must be also upward (so that the electric force on the ions is downward). Then, the two forces are balanced if

$F_E = F_B$

which translates into

$qE=qvB\\\rightarrow v = \frac{E}{B}$

Therefore, if the speed of the ions is equal to this ratio, the ions will go undeflected.

We can even calculate the value of E at which this occurs. In fact, we know that the ions are earlier accelerated by a potential difference $V=-3000 V$ , so we have that their kinetic energy is given by the change in electric potential energy: