Recent content by kuruman

In addition to @Steve4Physics's comments: 1. Please note that we prefer that you post your work in ##\LaTeX## which makes the equations more legible and easier to refer to. To learn how, please click on the link "LaTeX Guide", lower left above "Attach files." To preview (and possibly edit)...

So why is the title of the book "Around the World in 80 Days"? :rolleyes:

Several years ago I took a direct flight from Dallas to Beijing. Here is a relevant excerpt from the notes I kept during the trip. The International Date Line (IDL) runs between the North American and Asian shores through the Bering Strait. I watched “local time” displayed on the flight...

Perhaps, but I don't think so. The real force in this case is static friction which adjusts itself to provide the observed acceleration ##a_{rot.}=0## in the rotating frame. That's because in the rotating frame the man walks along a straight line at constant velocity relative to the platform in...

I assume that the pipe is supposed to drain under gravity. Based on the idea that the less time the water spends in the pipe the less likely it is to freeze, I would recommend researching the brachistochrone which literally means "shortest time" in Greek. Of particular interest is that a ball...

Another way of looking at this is from the standpoint of the wave. For positive ##x## at a particular instant in time ##t## and at position ##x##, the function ##f(x-vt)## return a specific value, say ##3## units. Time always increases. At a later time ##t'>t## must ##x## increase, decrease or...

In which case, if the system is taken to be the two masses plus string, one can immediately write $$F_{\text{net}}=(m_2-m_1)g\implies a=\frac{F_{\text{net}}}{(m_1+m_2)}=\left(\frac{m_2-m_1}{m_1+m_2}\right) g$$without bothering about the tension.

I will hazard a guess as to where OP's problem lies. Perhaps something like this. The second law is justified as a law because heat flowing from the low temperature to the high temperature reservoir has never been observed. Fine. However, if this kind of reasoning is valid for establishing a...

To @nataliaeggers: Let me elaborate a bit more along the lines presented by @jbriggs444. Suppose you have a collection of ##10^{24}## gas atoms in a metal container. These atoms are all moving in random directions colliding with each other and with the walls of the container. Furthermore...

Sure, but note that mechanical energy is the sum of kinetic plus potential energy. Therefore, in my expression, it is implied that $$\Delta E_{\text{mech.}}=\Delta K+ \Delta U$$no matter what you consider as the system.

I don't know about the water in your pan, but I know that I can use thermal energy to explain the change in kinetic energy of a book on my table that receives a sudden kick and slides across the table top until it stops. I can write total energy conservation from the moment the book starts...

Did you notice that your expression cannot possibly be correct because its numerator is the negative of the denominator and simplifies to ##a_1=-g##? This is free fall! Note that mass ##m_0## doesn't "know" (or care) whether there is a mass or an Atwood machine at the other end of the string...

The diagram on the right shows the Earth rotating with angular speed ##\Omega_0##. We are looking down the axis of rotation in an inertial frame. A tower of height ##h## is built at the Equator. Point A at the base of the tower is moving west to east with tangential speed ##v_A=\Omega_0R_E##...

Thanks to your nice drawing it is clear what's what. To @brotherbobby: The cross product vector ##\mathbf {\Omega}_0\times \mathbf v## is perpendicular to the plane defined by the axis of rotation and "up". This direction is East. The negative sign in front of the Coriolis term changes the...

There is a problem with OP's drawing. It is not clear at all which direction is "westward". Usually "west" is opposite to"east" which, according to the drawing, is ##-\hat i## or to the left. The Earth rotates west to east. If one uses the right hand rule rule, launching point P has tangential...