# Tagged Questions

112 views

### Whats the anti-torque mechanism in horizontal take-off aircraft?

In most helicopters there is the anti-torque tail rotor to prevent the body from spinning in the opposite direction to the main rotor. What's the equivalent mechanism in horizontal takeoff single ...
153 views

### Drag on a spinning ball in fluid

I am a physics newbie (high school level) and I am wondering what happens when a spherical object is spinning on the spot in a bunch of gas (no gravity here, just an imaginary physics sandbox). Am I ...
59 views

### Fluid flow in a hollow spring(helix)

Liquid flowing in a long hollow spring(helix). Any effects on the flow rate etc when the spring is stretched or compressed? When the stretching or compressing of spring is done at brisk speeds the ...
348 views

### Bernoulli's equation and reference frames

So I was thinking about this while driving home the other day. I've never been quite clear on why when you drive with the windows down air rushes into your car. I thought this might be explained by ...
138 views

### By how much will water resistance and upthrust slows down a fully submerged object?

Consider the following example: While running, I do work and I have a certain velocity and acceleration. When I'm in a pool (my feet are touching the bottom), I do the same work but, I have less ...
456 views

### At same level do these two pipe lines give same pressure of water?

Provided that the two pipe lines are of same length, same material and in the same level, is the water pressure in both the layouts same or different? PS: In 1st pipeline the turns are not ...
135 views

### Distance a curveball travels?

I've seen some discussions regarding the movement of a spinning object, say a curveball. However, all have been largely qualitative. I was wondering if anyone has seen or worked through a ...
665 views

### Is the static gauge pressure of a free jet always atmospheric?

Let's say I have a free jet of air leaving a pipe into the atmosphere. I know that the static gauge pressure at the pipe exit is equal to the atmospheric. But what about the static gauge pressure 10 ...
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### Is the pressure at the outer hole on a pitot static tube equal to atmospheric pressure?

I'm looking at a pitot static tube question right now and I just need some clarification. There is the outer hole on the pitot static tube, not the hole that the air stream goes through, but the other ...
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### How do I determine where the maximum air velocity around an object is?

I have a freestream of air directed at an object. Is there a way to find where the maximum air velcoty occurs with only having initial air speed and static pressure at the object?
281 views

### Calculating torque of actuators? [closed]

How do you calculate the torque of a brushless dc electric motor? How do you calculate the torque of a hydraulic motor? How do you calculate the push and pull force of a double acting hydraulic ...
222 views

### Which actuator is more effective: pneumatic, hydraulic, or electric? [closed]

For an system that amplifies strength by about two (press capacity of 400 lbs.), which would be the most practical, or the most compact? A pneumatic system that uses air cylinders or air muscles, A ...
1k views

How is the shape of the blades of an air fan determined? Trial and error, or is there a theory behind it? What are they trying to maximize, volume of air dislocated per rotation?
2k views

### Mechanics around a rail tank wagon

Some time ago I came across a problem which might be of interest to the physics.se, I think. The problem sounds like a homework problem, but I think it is not trivial (i am still thinking about it): ...