swansont

Problem: The fields don't actually protect the poles from radiation - moving charges will "orbit" magnetic field lines (F = qv x B), so what really happens is that the magnetic field protects the equatorial/temperate areas by redirecting some charged particles toward the poles. Ever wonder why they are called the Northern Lights? And it only affects charged particles. edit to add: another theory slain by an ugly fact

Problem: The fields don't actually protect the poles from radiation - moving charges will "orbit" magnetic field lines (F = qv x B), so what really happens is that the magnetic field protects the equatorial/temperate areas by redirecting some charged particles toward the poles. Ever wonder why they are called the Northern Lights? And it only affects charged particles. edit to add: another theory slain by an ugly fact

No. I think of degrees and radians as pseudounits - you need to keep track of them to be consistent, but they are an implied ratio (fractions of a circle) and as such don't really have any dimension.

No. I think of degrees and radians as pseudounits - you need to keep track of them to be consistent, but they are an implied ratio (fractions of a circle) and as such don't really have any dimension.

No object, or information, moves faster than c in that scenario. Relativity doesn't preclude two event from happening at times separated by less than d/c, it only precludes causal events from happening under those conditions.

No object, or information, moves faster than c in that scenario. Relativity doesn't preclude two event from happening at times separated by less than d/c, it only precludes causal events from happening under those conditions.

The reaction force isn't, but the normal force is. At the microscopic level, the contact force between objects is the repulsion of electrons.

The reaction force isn't, but the normal force is. At the microscopic level, the contact force between objects is the repulsion of electrons.

The stuff in bold is absolutely wrong. Action and reaction forces are always of the same type. If the action force is gravitational, so is the reaction force. It is important to remember that action and reaction forces act on different objects. The action is the gravitational force the earth exerts on the object, so the reaction is the gravitational force the object exerts on the earth. Since the motion of an object is dependent upon the force acting on it, when you draw a free-body diagram, thre will never be an action-reaction force pair in it.

The stuff in bold is absolutely wrong. Action and reaction forces are always of the same type. If the action force is gravitational, so is the reaction force. It is important to remember that action and reaction forces act on different objects. The action is the gravitational force the earth exerts on the object, so the reaction is the gravitational force the object exerts on the earth. Since the motion of an object is dependent upon the force acting on it, when you draw a free-body diagram, thre will never be an action-reaction force pair in it.

Figure out the speeds for the two cases, using an arbitrary distance. The speeds add - so figure out the time for that same arbitrary distance. The most rigorous way would be to use x, but the value will drop out, so you can e.g. make it a 90 meter escalator.

Figure out the speeds for the two cases, using an arbitrary distance. The speeds add - so figure out the time for that same arbitrary distance. The most rigorous way would be to use x, but the value will drop out, so you can e.g. make it a 90 meter escalator.

There is no phase change, since the reflecting light is within the lens. It doesn't see a higher index material. Light reflecting off the plane is in air and does see a higher index, so that light undergoes a [math]\pi[/math] phase change. More

There is no phase change, since the reflecting light is within the lens. It doesn't see a higher index material. Light reflecting off the plane is in air and does see a higher index, so that light undergoes a [math]\pi[/math] phase change. More

No, the reaction force is always equal in magnitude and opposite in direction, by Newton's third law. But that's irrelevant - the reaction force is the gravitational force the block exerts on the earth, and we don't care about that. The free-body diagram needs to show all the forces acting on the block. The surface exerts a normal force, which is (by definition) normal, or perpendicular, to the surface.

At constant T, PV is also constant. In a mixture, partial pressures add to be the total pressure.

You get a bright fringe at the center.

Yep.

The resultant force is in the direction of the acceleration. In this case it's parallel to the incline.

21, I think, in all states. Technically it's up to the states to decide, but there was a time that some states had it at 18, and there were many instances of people driving over state borders to drink, and that was a problem. As I recall it, the federal government eventually said (about 20 years ago), basically, that the states were free to choose, but if they didn't raise the drinking age to 21 they would lose federal funding for highways (lots of $$). So those states who weren't at 21 "chose" to raise the age.