Wednesday, 2 January 2008 - 9:00 PM EST

1.  You could determine the sign of the charge on the comb if you rubbed a glass rod with the silk.  Then hold the comb and the rod close to each other.  If the comb is attracted to the rod it has a positive charge. If the comb is repelled by the rod it has a negative charge.

2.  Because water molecules are polarized, they are attracted to ions in the air.  If the charge of the ion is strong enough, it will bring several water molecules close together and create the posibility of condensation and hydrogen bonding between the water molecules.

3.  Electricity is almost always stronger than the force of gravity, especially when dealing with small objects.  The charged rod creates and induced charge in the paper and if the electric attraction is great enough to overcome gravity, the paper rises and latches on to the rod.

4.  Both the gravity and electricity equations measure forces.  They are similar because a measure quantity (mass and charge respectively) are multiplied along with a constant and the product is divided by the square of the distance between the two objects.  The equations are different because the two constants are significantly different. 

Wednesday, 2 January 2008 - 9:45 PM EST

1.       If you took an object with a known charge (Matt used the example of the rod rubbed with the silk, which would have a negative charge), and held it to the comb, the charge could be determined.  Because opposites attract, a comb with a positive charge would be attract the rod and one with a negative charge would repel.

2.       Water molecules possess two parts hydrogen (positive) and one part oxygen (negative), this allows polarization in the water molecule to occur. Just like the pieces of paper that we discussed today, the water molecules polarization means that it can be attracted by ions in the air. If there are enough molecules attracted, then the water molecules will become fog or rain.

3.       Because the pieces of paper become polarized by the charged ruler, and because the force of electricity is a more powerful one than gravity, the paper can often be lifted against gravity. However, this is harder on a rainy day because the humidity in the air attracts the charge as well, weakening its use on the papers.

4.       Coulomb’s Law and the Law of Gravitation of very similar because they both describe attractive forces. The only real difference is the constant, which is much smaller for gravitation, causing it to be a weaker force. Both equations describe the same basic effect though, with the attractive forces (mass or charge) being directly proportional to gravitational or electrical force. In each case, the square of the distance between the objects is inversely proportional to the force, showing that more distance leads to a weaker force in both of the equations.

Wednesday, 2 January 2008 - 10:11 PM EST

if you charge a glass rod, the charge will be negative, so if the comb attracts the glass rod, the charge on the comb is positive, if it repels, it is negative.

Because of its molecular structure, water can arrange itself so it is polarized, so droplets are attracted to the positive charge of ions or negative charges of electrons

The plastic ruler possesses a charge, so the neutral pieces of paper can polarize themselves so that the opposite charge faces the ruler and thereby is attracted to it.  On a humid day, the water in the air would take away from the ruler’s charge, as mentioned above because water too can polarize when in a neutral form to take charge from objects.
Both laws are similar in that they depend on a the product of a constant and the measure of force of two bodies divided by the distance squared between the two bodies.  The two equations also measure attractive force between two objects.  However, because the gravitational constant is so small and the electrical constant so large, it is illustrated that electrical force is stronger than gravitational force.  Also, mass plays no role in the electrical equation, only the atomic make up of each body, whereas the mass in the gravitational equation is key to a significant amount of attraction.  Thus, small bodies can build up a significant amount of attractive force between them via electricity, but bodies must be very large for gravity to even play a role

Wednesday, 2 January 2008 - 10:12 PM EST

sorry the numbers didn't show up and it looks really lame, it had them from word when i submitted but didn't show up

Wednesday, 2 January 2008 - 10:28 PM EST

1. Basically the same as correnti said, you can rub a glass rod with the silk and see if it attracts or repels the comb. If it attracts, it has a positive charge and if it repels, the comb has a negative charge.

 2. Since water molecules are polarized, they are attracted to the ions in the air, and when enough water moleucles are brought together in the same place, they have a tendency to form water droplets

3. since the ruler is now charged, it polarizes the pieces of paper through induction and creates an attractive force between the two. If that force is strong enough to overcome the force of gravity on the paper the paper attaches to the rod. On a humid day, the polarized water droplets in the air leech the charge off the ruler and cause the attractive force between the paper and ruler to become weaker.

4. Both equations measure the force between objects. They both include a constant multipled by two variables and divided by the distance between them. Coulomb's law is different because it uses the magnitudes of the electrical forces due to the fact that they are the absolute values. 

Wednesday, 2 January 2008 - 10:32 PM EST

1.  Like Matt said.  If you were to rub a glass rod with the silk we know that it becomes negatively charged.  Therefore we know that if the comb is attracted to the glass rod it needs to be oppositely charged meaning it would be positively charged.  If it were repelled we would know the comb is negatively charged.

 2. The ions would attract more polarized water molecules that would form together into water droplets and would remain in the area.

3.The ruler would have either a positive or negative charge that would attract either electrons or protons depending on the charge.  Since the electromagnetic is stronger than gravity it can pick up the pieces of paper.  On a humid day the polarized water molecules in the air attract more of the electrons in the ruler making it harder for the ruler to hold a charge.

4. In both equations you will find a similarit that in both, the product is a force and it is found by multiplying some quantity by a constant and divided by the distance between two objects that are discussed in the equation.  The difference is that the constants are vastly different for each equation.

Wednesday, 2 January 2008 - 11:00 PM EST

1. You can determine the charge by holding the charged comb up to the rod charged by silk. According to the readings in class, rubbing silk against a plastic rod results in a negative charge. Therefore, if the comb is attracted to the rod, it's positively charged and if it's repelled it is negatively charged.

2. Since water is two parts hydrogen and one part oxygen, molecules of water are polarized. Therefore, even without having a charge they can be attracted just like the paper with the comb demo. If enough of these molecules condense, they can bond together to form rain or fog.

 3. Paper can be picked up by a charged rod because the neutral paper can polarize. Therefore the oppositely charged ions in the paper will be attracted to the comb while the same charge will be repelled. The power of electricity then overcomes the power of gravity, resulting in the paper sticking to the comb. It's harder when it's humid because some of the charge gets absorbed in that, making air an even worse conductor.

4. Coulomb's law and Newton's Universal Law of Gravitation are similar in that they're both a constant multiplied by the forces of two objects and divided by the distance between them squared. Both laws show that the further away an object is, the weaker the force. However, the constant K is much larger than the constant G because electricity is stronger than gravity.

Wednesday, 2 January 2008 - 11:35 PM EST

1. I do agree with what every one has said so far since there is nothing wrong with their approach. If you take an object with a known charge such as the glass rod and bring it close to the charged plastic comb. You are able to tell the unknown charge of the comb by weather if it will attract which means that it is positively charged since opposite charges attract. If the comb is repelled by the glass rod then that means that it has the same charge which is negative since like forces will repel each other.

2.  The answer lies in the make up of the water or H2O atom. In this Atom it is two parts hydrogen which are positively charge and one part oxygen which is negatively charge. Since it has both kinds of charges within this atom this means that it can be polarized. And that is exactly what happens to the water atom it becomes polarized and then it’s attracted to the electron ions in the air. If there is a strong enough concentration of electrons in the air then it will be able to attract enough H2O to form fog or the rain droplets.

3.  When the plastic ruler is rubbed with a cloth it will become charged and when it is close to the neutrally charged pieces of paper. It will cause them to be polarized which means that they now will be attracted to the comb. In this case the electromagnetic force experienced by the paper due to the comb’s presence is greater then the gravitational force that is exerted on the paper by the Earth. On a humid day the air is saturated with more H2O particles then on a dry day. This means that the H20 particles will act in the same way that I described in the last part . The rod is no longer just attracting the paper it is now attracting the H2O atoms which means that the force that the paper experiences is less then it would experience on a dry day. That is why that situation is more difficult on a humid day due to the fact that the comb electromagnetic force is now divided up.

4.  Gravitational force and electromagnetic force are two of the forces that occur in nature and are able to interact with objects over long distances. Both equations depend upon the distance squared between the objects and both depend on certain characteristics of the objects. In the case of coulomb’s Law it will depend on the charge of the objects that are interacting with each other and in the case of the Newton’s law of Gravitation it will depend on the mass of the objects that are interacting with each other. The only major difference is the constant that the two equations are multiplied by. Electromagnetic constant is greater then the gravitational constant.

Wednesday, 2 January 2008 - 11:43 PM EST

1.) You need an object with an known charge and if the comb is attracted to it then the comb has the opposite charge of the object with the "known" charge. If they repel each other then they have the same charge

2.) Water molecules are polarized therefore they neutralize the ions in the air. The higher the net charge of a certain ion the more water molecules it will attract.

3.) When dealing with small objects, electricity is almost always stronger then the force of gravity. So when the ruler is charged by the cloth it has the ability to pick up the piece of paper. This is not as effective on a humid day because the ruler because neutralized quicker due to the massive amount of water molecules in the air. 

4.) The equations are similar because a measurement is multiplied by a constant( mass for gravity and charge for electricity). These products are then diveded by the square of the distance of two objects. However the area where they differ is that the constants are different and this illustrates the difference between electricity and gravity.

Thursday, 3 January 2008 - 10:06 AM EST

1.  One way to determine the sign of the charge on the pocket comb would be to hold it up next to a glass rod charged similarly to the one in class.  If the two repelled each other, the comb would have a negative charge, however, if the two attracted each other, the comb would have a positive charge.

2.  Water molecules are polarized, that is, the electrons move to one side of the molecule and protons move to the other.  Because of the polarization, the water molecules are attracted to the ions or electrons in the air, and when a number of molecules come together, they will form a drop of water.

3.  A plastic ruler rubbed with a cloth has the ability to pick up small pieces of paper due to its electrical attraction force.  In the case of very small objects, the electrical force will almost always be greater than the gravitational force, therefore, the electrical force from the ruler creates a charge by induction in the paper and lifts them up off the table.  This is more difficult on a humid day because all of the water molecules in the air are able to steal charge from the ruler and the electrical attraction force between the ruler and pieces of paper decreases.

4.  The major difference between these two equations is the constant in the numerator.  The constant in Coulomb's Law is significantly greater.  The other difference is that you are multiplying two charges together in the numerator in Coulomb's Law rather than two masses in the numerator of Newton's Universal Law of Gravitation.  The similarities are that the two equations are of the same form and they both have the radius squared in the denominator.

Thursday, 3 January 2008 - 10:07 AM EST

1. If you charge a pocket comb by rubbing it with a silk scarf, you can determine the sign of it charge by holding close to another object with a known charge. If it attracts to it then they have opposite charges and if it attracts to it then they have the same charge.

2. We know that water molecules are polarized, therefore, they become attracted to the ions floating around in the air.  From here as more water molecules come together, rain droplets form.

3. Since the ruler was charged it creates an electric force.  Then it is able to polarize the pieces of paper through induction as bob said and the ruler is attracts the pieces of paper to it being that electricity is almost always stronger than the force of gravity.  If it was a humid day outside, it would be difficult because the water droplets are polarized and they would take away some of the charge from the charged ruler causing the attraction between the ruler and the pieces of paper weaker.

4. Some similarities are that in both of these equations you measure forces. You also have a constant that is being multiplied in both, also each with two variables.  And, you divide both by the distance squared between the two objects.  A difference is that both of the constants are significantly different in value from each other because the electricity has as strong force than gravity.