Tagged Questions

45 views

How fast could a football drop? [closed]

Suppose we have a perfect spherical football with d=22.5cm and m=420g. The football has a initial vertical speed of v(around 20m/s, not sure if it will cause a turbulence) and zero angular speed. If ...
132 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 ...
215 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 ...
68 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 ...
369 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 ...
145 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 ...
490 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 ...
137 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 ...
703 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 ...
172 views

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 ...
112 views

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?
293 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 ...
231 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 ...