A couple of physics questions

[thebillsfan]

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Does a moving charge experience a force when moving through its OWN magnetic field?

Is the velocity of a sound wave faster in gas or solid? I would think solid since all the vibrating atoms are right next to each other, but EK says that velocity of a sound wave through a gas is on the order of magnitude of the random velocity of its molecules, which is pretty fast.

Does doubling the frequency of light double the # of photons or double the energy of the same # of photons?

Can someone explain Gauss's law qualitatively, and the features of Gauss's law that are relevant for the MCAT?

Also, what is the result of putting batteries either in parallel or in series?

Finally, is it important to at all be familiar with the cgs and fps unit systems?

 

[G1SG2]

Does a moving charge experience a force when moving through its OWN magnetic field?

A charged particle never responds to its own electric or magnetic field-only to external fields.

Is the velocity of a sound wave faster in gas or solid? I would think solid since all the vibrating atoms are right next to each other, but EK says that velocity of a sound wave through a gas is on the order of magnitude of the random velocity of its molecules, which is pretty fast.

Solid, because the solid has a greater resistance to compression (the greater the elastic component).

Does doubling the frequency of light double the # of photons or double the energy of the same # of photons?

Increasing the frequency increases the energy of the electrons. However, I think increasing the intensity increases the number of photons but does not increase the energy of the electrons.

Can someone explain Gauss's law qualitatively, and the features of Gauss's law that are relevant for the MCAT?

I hate Gauss' law. I covered this in Physics II but never understood it well enough to explain it to someone. Hopefully someone can explain it to the both of us, lol. It can potentially pop up on the MCAT, though since it's on the PS topics list. Yet, none of the prep books cover this topic.

Also, what is the result of putting batteries either in parallel or in series?

Not sure.

Finally, is it important to at all be familiar with the cgs and fps unit systems?

No. Just know the SI units.

 

[austinap]

Also, what is the result of putting batteries either in parallel or in series?

In series, the voltages add.

In parallel, the voltage is unchanged, which means for MCAT purposes, you can treat it as a single battery. (IRL, the ability to produce current is effected, but ignore this for now).

I've never actually seen a circuit problem with more than one battery on the MCAT.

 

[AandOtimesZero]

How is this solved? I don't understand the math.

30t-5(t^2)=0 , so

5t(6-t)=0, so

t=6

This is from a Kaplan physics problem

 

[dextor2003]

How is this solved? I don't understand the math.

30t-5(t^2)=0 , so

5t(6-t)=0, so

t=6

This is from a Kaplan physics problem

they just factored out a 5t and solved for t

 

[sangria1986]

In series, the voltages add.

In parallel, the voltage is unchanged, which means for MCAT purposes, you can treat it as a single battery. (IRL, the ability to produce current is effected, but ignore this for now).

I've never actually seen a circuit problem with more than one battery on the MCAT.

all this is true but remember that in series
they only add if the batteries are lined with positive and negative terminals next to each other. However if the same terminals face each other then they are subtracted w the higher one being the positive and the lower voltage as the negative. I.e. 20 v and 15 v battery in series w same terminals facing each other-total voltage is 5. Not -5.

 

[sangria1986]

A charged particle never responds to its own electric or magnetic field-only to external fields.

Solid, because the solid has a greater resistance to compression (the greater the elastic component).

Increasing the frequency increases the energy of the electrons. However, I think increasing the intensity increases the number of photons but does not increase the energy of the electrons.

I hate Gauss' law. I covered this in Physics II but never understood it well enough to explain it to someone. Hopefully someone can explain it to the both of us, lol. It can potentially pop up on the MCAT, though since it's on the PS topics list. Yet, none of the prep books cover this topic.

Not sure.

No. Just know the SI units.

Gaussian surface-charg inside is zero