# Tag Info

### Is it really the Tension in the rope that pulls the pulley?

Consider a segment of the rope with length $r\,\mathrm d\theta$, where $r$ is the radius of the pulley: The tensions on either side of this segment are not quite antiparallel, so there is a net force ...

### Is it really the Tension in the rope that pulls the pulley?

Yes, if we have a smooth rope and a frictionless pulley, the pulley is acted on by normal forces between the pulley and the rope. These normal forces will be different all the way along the part of ...

### Apparent weight due to the rotation of earth

You are implicitly assuming that the normal force and the force due to gravity act in parallel and opposite directions. This cannot be correct, except at the equator, since their resultant (which is ...
Accepted

### Can a block set on a inclined plane fall vertically downwards

Can a block set on a inclined plane fall vertically downwards Only if the mass of the incline, $M$, were zero. Since the only external forces acting on the combination of the two blocks are vertical (...

### What is the microsopic reason why hot air rise?

You are getting a macroscopic explanation because this is a macroscopic effect. Microscopically, air molecules move in random directions with approximately the speed of sound. (For mean thermal ...

### Can we have motion in systems where inertia is neglected?

I'm not completely sure I fully understand your question, but I'll try to give you an answer... It might help to think of this problem in a pseudo-relativistic context, wherein the physical motion of ...

### Is this possible?

No. This would be like trying to move yourself to the right by pulling on your left arm with your right hand.
1 vote

### Deflecting a belt under tension

I'm voting with your colleague. Everything comes down the the force it takes to deflect the belt at the point of contact, and since this is for a static situation, action equals reaction. The ...
1 vote

### Is it really the Tension in the rope that pulls the pulley?

Consider a small segment of rope $AB$ located at an angle of $\theta$ is in the left digram. The two tension forces $T$ do not act along the same line of action as shown in the middle diagram. The ...
1 vote

### Can we have motion in systems where inertia is neglected?

We sometimes assume a body has negligible mass, such as a rope in a pulley system where the pulley and weights on the ends of the rope have much greater mass than the light rope. This simplifies the ...
1 vote

### Can we have motion in systems where inertia is neglected?

It is not clear what is meant by inertia is neglected: Small/huge inertia It could be that the inertia is so small, that particle experience huge acceleration. We do often use this kind of an ...
1 vote

### Can friction or normal force be undetermined?

In general, there is no reason why all the reaction forces can be determined in a problem. Your intuition is biased by all the exercises you were assigned in an academic setting, which were hand-...
1 vote
Accepted

### Why do radial forces do no work?

Recall the definition of work done, $W$ by a force, $\textbf{F}$, over a change in displacement $\textbf{x}$ \begin{equation} W = \textbf{F}\cdot\textbf{x}. \end{equation} In a circular orbit, the ...
1 vote

### What is $V$ in Buoyant force $V\rho g$?

V is the volume of fluid displaced. If the iron block has mass $M$ and we assume that the box does not sink after its introduction then there must be an additional $Mg$ buoyant force supplied, which ...
1 vote
Accepted

### Weight as tension

It's not the weight that becomes a third tension. The third tension is the tension in the vertical wire. So you actually have three tensions balancing at the common point of the three wires. It just ...

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