virtual physics

The title of the Project: Atoms, ions, and isotopes  Purpose of the work: Practical part Choose “Atom” to start the virtual experiment.  This is a little instruction to the virtual experiment. Part 1. Atom Virtual experiment. Step 1. Build a helium atom. Add 2 protons, 2 neutrons and 2 electrons.  Step 2. Notice that the protons and neutrons are in the center, which is called nucleus. The constituents of the nucleus are called nucleons. Step 3. Notice that the electrons go to an orbit around the nucleus, which is called orbital.  Step 4. Switch to the cloud model. The electrons become an electron cloud. It means that the electrons are most probably in the area, depicted by the cloud.   Step 5. Notice that the atom is neutral. The charges of an electron and a proton are equal in magnitude, but different in sign.  Step 6. Make a conclusion. Part 2. Isotope Virtual experiment. Step 1. Switch back to the orbit model. Take away one neutron. Now this is an isotope of the helium atom, called Helium-3. This is a stable isotope. Step 2. Take away another neutron. This is another isotope of the helium atom, called diproton. This is an unstable isotope, meaning it can decay very quickly.  Step 3. Note that altering the number of neutrons you can make an isotope.  Step 4. Make a conclusion.  Part 3. Ion Virtual experiment. Step 1. Go back to a helium atom.  Step 2. Add another electron. This is no longer an atom, this is a negatively charged ion, since there are more negatively charged particles.  Step 3. Take 2 electrons back. Now it is positively charged ion since there are more positively charged particles.  Step 4. Note that altering the number of electrons you can make an ion, either positive or negative.  Step 5. Make a conclusion.  Conclusion Atom is neutral, it contains equal number of electrons and protons and some number of neutrons. Ions are charged particles; they can be negatively or positively charges. To create an ion, add or subtract one or more electrons. Isotopes have different number of neutrons than the atom. 

The title of the Project: Friction Purpose of the work: Practical part This is a little instruction to the virtual experiment. Virtual experiment. Step 1. Notice that the upper book has microscopic imperfections on its surface.  Step 2. Take the upper book and start to rub it a little. When two surfaces rub against each other, the irregularities and microscopic imperfections on their surfaces come into contact. As they slide past each other, the molecules at these points experience resistance due to intermolecular forces. Step 3. Notice that the temperature increases according to the thermometer and the particles start to oscillate faster, when the books are rubbed. This is because the resistance results in the conversion of mechanical energy into thermal energy. Step 4. Make a conclusion.  Conclusion When two surfaces slide on each other their microscopic imperfections come into contact and experience intermolecular forces which result in resistance to the motion. The resistance to motion is friction. Friction is essentially the force that opposes the relative motion of surfaces in contact.

The title of the Project: Newton’s second law Purpose of the work: Practical part Choose “Acceleration” to start the virtual experiment. This is a little instruction to the virtual experiment. Part 1. Net force Virtual experiment. Step 1. Apply some force to the body such that it moves. Notice that the net force is not zero. How does the acceleration change? Step 2. Increase the applied force in small increments. Notice that the net force on the body increases. How does the acceleration change?  Step 3. Increase the friction coefficient, such that the sliding friction force is greater than the applied force, but the net force is not zero. What happens? How does the acceleration change? Step 4. Notice that the net force changed the direction, and the acceleration became negative.  Acceleration and net force are vector quantities, therefore the change in direction changes these quantities. Step 5. Wait until the body stops. The net force is zero again. Decrease the friction coefficient. What happens? The net force increases and becomes positive again and so does the acceleration. Step 6. Make a conclusion. Part 2. Mass Virtual experiment. Step 1. Restart the experiment. Apply some force to the body such that it moves. Notice that the net force is positive and the acceleration as well. Step 2. Add another box. Decrease the friction coefficient such that the net force doesn’t change. How does the acceleration change?  Step 3. Make a conclusion. Conclusion Acceleration is directly proportional to the net force that acts on the body and inversely proportional to the mass of the body as Newton’s second law states. 

The title of the Project: Sliding friction Purpose of the work: Practical part Choose “Friction” to start the virtual experiment.  This is a little instruction to the virtual experiment. Part 1. Friction coefficient Virtual experiment. Step 1. Apply some force to the body such that it starts to move. Pause the experiment. Notice how much the sliding friction is.  Step 2. Increase the friction coefficient. How the sliding friction changed?  Step 3. Decrease the friction coefficient. How the sliding friction changed? Step 4. Make a conclusion.  Part 2. Normal force Virtual experiment. Step 1. Start the experiment again. Apply some force to the body such that it starts to move. Pause the experiment. Notice how much the sliding friction is.  Step 2. Note to check the dependence of the sliding friction on the normal force we change the mass of the object since the normal force is equal to the force of gravity. Hence to change the normal force we should change the force of gravity and to do so we change the mass of the object.  Step 3. Add another box to increase the mass. How the sliding friction changed? Step 4. Change the object for a lighter one. Apply some force. How the sliding friction changed? Step 5. Make a conclusion. Conclusion The sliding friction is directly proportional to the friction coefficient and the normal force. 

The title of the Project: Static friction  Purpose of the work: Practical part Choose “Friction” to start the virtual experiment.  This is a little instruction to the virtual laboratory.  Virtual experiment. Step 1. Apply some force to move the body. What happens? Notice that the body doesn’t move since the friction force is the same as the applied force. Step 2. Increase the applied force. What happens? The friction force increases as well. Why? This is called the static friction. It will be increasing until the applied force will become greater than the sliding friction force.  Step 3. Increase the applied force with smaller increments. Notice when the body starts to move. What is the sliding friction force?  Step 4. Make a conclusion. Conclusion The static friction is the force of friction on an object that is not moving. The static friction is applied to the resting body and the sliding friction is applied to the moving body.

The title of the Project: Motion Purpose of the work: Expected results: Practical part To start the virtual experiment press “Motion” button. This is a little instruction on the virtual laboratory. Part 1. Motion Virtual experiment. Step 1. Apply some force to the body. What is the speed of the body? Step 2. Apply more force to the body. How does the speed change? The speed increases as long as the force acts on the body. Part 2. Inertia Virtual experiment. Step 1. Increase the mass of the object by adding another box. Do you notice any changes? Step 2. Change the object, place the fridge, which mass is much greater. What changes? The more massive the body the more difficult it is to move the body.  Conclusion Applying some force onto the body makes the body move and increase its speed, if it is affected by a pushing force. The more the mass of the body the harder it is to put the body into motion. This is the concept of inertia, which is the tendency to remain unchanged. The more massive the body the harder it is to change its state of rest into of motion.

The title of the Project: Net force Purpose of the work: Expected results: Practical part To start the virtual experiment press “Net force” button. This is a little instruction on the virtual laboratory. Virtual experiment. Step 1. Place 2 people that are the same size the same distance away from the cart. What will happen? The forces that act on the cart are balanced out, so the net force is zero and the cart will not move. Step 2. Place 2 people that are the same size different distances away from the cart. What will happen? The forces that act on the cart are balanced out, so the net force is zero and the cart will not move. Step 3. Place 2 people that are different sizes the same distance away from the cart. What will happen? The forces that act on the cart are out of balance, so the net force is not zero. The cart moves to the direction of greater force. Step 4. Place 2 people that are the different sizes different distances away from the cart. The forces that act on the cart are out of balance, so the net force is not zero. The cart moves to the direction of greater force. Make a conclusion. Conclusion When the net force is other than zero, the forces are unbalanced and when the net force is zero, the forces are balanced. To calculate net force, take into account the direction of the forces. For oppositely directed forces use subtraction and for forces directed in one direction use summation.

The title of the Project: Newton’s law of gravitation Purpose of the work: Expected results: Practical part This is a little instruction on the virtual laboratory. Virtual experiment.  Step 1. Choose scientific notation and constant size for convenience. Step 2. Change the distance between the bodies. How do gravitational forces change?  Step 3. Change the mass of the first body. How do gravitational forces change?  Step 4. Change the mass of the second body. How do gravitational forces change? Make a conclusion. Conclusion According to Newton’s law of gravitation the gravitational force is proportional to the masses of the bodies and inversely proportional to the distance squared.

The title of the Project: Interaction of electric charges  Purpose of the work: Expected results: Practical part This is a little instruction for the virtual laboratory. Part 1. Electrification process Virtual experiment. Step 1. Rub one balloon onto the sweater. What happens? Balloon gets attracted to the sweater.  Step 2. Notice that the balloon gets charged negatively and the sweater gets charged positively. Make conclusion.  Part 2. Interaction of charged bodies Virtual experiment. Step 1. Take another balloon and rub it onto sweater.  Step 2. Take both balloons, how will they interact with each other?  Step 3. Notice that both balloons are negatively charged. Make a conclusion. Part 3. Neutral and charged bodies Virtual experiment. Step 1. Take one balloon and bring it to the wall. What happens? The balloon gets attracted to the wall, although the wall is neutral. Step 2. Notice that negative charges in the wall gets displaced slightly.  Step 3. Remove the wall. What happens next? Make a conclusion. Conclusion Two neutral bodies can be charged by rubbing to each other. Like charges repel and opposite charges attract.

The title of the Project: Charging by friction Purpose of the work: Expected results: Practical part This is a small instruction for the virtual laboratory. Virtual experiment. Step 1. Make John rub the carpet with his leg. What happens? John acquires some negative charge because of friction between his leg and the carpet. Step 2. Make John touch the doorhandle, which is made of conducting material. What happens? As John touches the doorhandle, the charges start to move to the conducting handle and resulting in sparkling. Step 3. Make a conclusion.  Conclusion When two neutral bodies are rubbed there will be some transfer of electrons from one body to the other one, which is called charging by friction.