# Search results

1. ### Fan-motor system resonance problem

Has the impeller been replaced? If so, have both resonated at the same rotational speed? Have both been balanced, both statically and dynamically? Same shaft for both impellers? Could you explain a little more about the fluid being transferred? Is it a gas carrying no solids or mist? If not...
2. ### 2-D Momentum Problem -- Elastic collision of two spheres

What horizontal plane are you referring to? The plane on which the balls are sliding or rolling on, or the one perpendicular to the shown picture and containing the trajectory of A?
3. ### Fan-motor system resonance problem

Welcome, @ArnoVonck ! How have you determined the 18.1 Hz impeller frequency? Should not this value be equal to the control frequency if motor and fan are directly linked? How would you describe the resonance of the system? What is the direction of the greatest oscillation? Could it be that...

5. ### Wiesen Mechanical Aptitude Test

Thinking of the consequences of failure only robs the precious energy and determination that help you overcome the challenge. Negative thinking induces paralyzing fear; resolution and positive action can and should replace it. Move your feet from the brake pedal onto the accelerator. :smile...
6. ### Wiesen Mechanical Aptitude Test

It seems to be a simple test for someone who is well rested, worry-free and knows the principles. https://www.practiceaptitudetests.com/mechanical-reasoning-test.pdf https://psychometric-success.com/aptitude-tests/test-types/wiesen-test-of-mechanical-aptitude Your competitors will not be as...
7. ### Why haven’t we made blow up wings to fly with them

Welcome, @kingsbishop ! It is different for wings because they don't have the solid connection to Earth that your bar for chin-ups has. Wings need to move through air quick enough to create a semi-solid support from the surrounding air. That semi-solid cushion of air can't sustain the wings...
8. ### I Velocity of The Plug

Isn't this similar to a balance with different weights at both ends, naturally seeking a balance state? You could replace the piston with a few drops of oil or a big bubble of air, I believe.
9. ### I Rolling ball, change of direction

Forces are associated to accelerations. How do you believe the trajectory will change?
10. ### Prolonging the Life of Poorly Accessible Rusted Steel

Yes, fresh fluid will greatly help. It seems that your tube is suffering a pitting corrosion. If so, many more pin-holes are currently developing. Please, see: https://corrosion-doctors.org/Corrosion-History/Rusting.htm You can look up "Rust remover jelly" for local options. Loctite has good...
11. ### Prolonging the Life of Poorly Accessible Rusted Steel

Rust may be working its way out, since brake fluid is highly hygroscopic. Also, when one branch fails, most cars lose pressure in one front brake and the opposite rear brake (rather than both front or both rear calipers). There are commercial products that stop the rust without the need for...
12. ### Penetration of a stake as it goes deeper into the soil

I believe it would not, as friction does not depend on area. I may be wrong, because I don't know anything about how different types of projectiles perform.
13. ### I Contemplating Gyroscopic Forces for fighting robot weaponry

Could the single drum be horizontal instead?
14. ### Two roads meeting a river at different angles (heights and distances)

I believe the mistake is in the 3 miles distance. For the values of the response to be correct, the distance from crossing to river via BC should have been 5.0 miles.
15. ### Recommendations for someone new to mechanics (learn it for building a robotic arm)

Welcome, @kamalMKA ! Do you have specific school assignment? if so, could you show us the scope and degree of difficulty of your project?
16. ### B Hydrodynamics Effects

Then, for the second part of the video you were referring to the sucking effect between hose end and flat lid. This happens because the Bernoulli effect, as the fluid velocity under the hose nozzle is greater than the one above. Please, see: https://en.wikipedia.org/wiki/Bernoulli%27s_principle
17. ### Penetration of a stake as it goes deeper into the soil

Welcome, @byarble ! Friction is the main thing to overcome in that case, unless your stake hits solid rock. Power actuated pins into steel beams are also hold in place by friction. The normal force comes from the elasticity of the deformed metal into which the pin is forced.
18. ### Angular acceleration problem for a pulley used to raise an elevator

Go back to post #4. Please, see: http://hyperphysics.phy-astr.gsu.edu/hbase/rotq.html#rq Then, try again. :smile:
19. ### I What is torque exactly?

It is a concept. Please, see: http://hyperphysics.phy-astr.gsu.edu/hbase/rotv.html#rvec1
20. ### Engineering Stress-Strain question -- The maximum elastic elongation of a steel sample

Could it be percentage?
21. ### Moment of inertia question for two plates welded together

The weld is calculated based on its cross-area times length besides yield stress. If we are still discussing two plates of Aluminum, both being 2" tall, and 1/2" thick, please consider how small this cross-section, which resists bending is. Any welding or drilling will weaken the main 2" tall...
22. ### Moment of inertia question for two plates welded together

No, more like this:
23. ### Friend can, add, subtract, multiply, divide, square root, square, in his head

I worked with an old engineer (80 years old!) who could do relatively simple calculations mentally and tell me the proper result before I could do the same with a hand calculator. He always finished first and never made a mistake. He did not have any special job, but while working together, he...
24. ### Moment of inertia question for two plates welded together

No, I wouldn't consider it as one bending-resistant effective piece. You would be increasing the cross-section, but stress on the welding would be too big.
25. ### Moment of inertia question for two plates welded together

By clicking on the link located at the bottom right corner of each page of that first link, you will be taken to the next page, which has some explanation and comparison of resistance to bending between beams formed by attached and detached layers of material. The welding creates a path for the...
26. ### Engineering Frame Statics Problem

Apologies about the delayed response. Your work looks good, but your value of Dx is incorrect. Member DE acts as a beam supported at both ends, not like a cantilever beam. That is because pivot E can't provide any reactive moment. Simultaneously, pin D is not free to rotate around pivot E under...
27. ### Power and Efficiency without mass?

Welcome, @sbrads87 ! The ball is in free fall. Please, see: https://en.wikipedia.org/wiki/Free_fall
28. ### Moment of inertia question for two plates welded together

What other way could it be? Please, see: https://mathalino.com/reviewer/mechanics-and-strength-of-materials/superimposed-or-built-up-beams https://mathalino.com/reviewer/mechanics-and-strength-of-materials/spacing-of-rivets-or-bolts-in-built-up-beams
29. ### Vector sample problem -- Force components on a spring mechanism

:oldconfused: The represented guide for that wheel (pushing or pulling the spring) is limiting the direction in which the spring is receiving any force, which is horizontal, rather than vertical.
30. ### Box Beam stress problem with welding

You could increase the radius of the bend, and then anneal the plates.
31. ### Box Beam stress problem with welding

But you would greatly increase the area moment of inertia to resist bending. If heat is a problem, you could resort to mechanical fastening using rivets or bolts or even self-drilling metal screws. Filling the hollow interior with a solid would prevent the walls to be deformed and less stress on...
32. ### A Practical use of an overall heat transfer coefficient?

I would say yes. The coefficient modifies the product of area and temperature difference to produce a value of thermal energy flow. That flow rate is greatly affected by the conditions of the film of fluid located closest to the walls, like velocity, turbulence, viscosity, hard deposits on the...
33. ### A Practical use of an overall heat transfer coefficient?

The coefficient should change is the flow velocity or diameter of the pipes are changed.
34. ### Box Beam stress problem with welding

Could you change the section to be welded from perpendicular to angled? Could you weld plates onto top and bottom of beam? Please, see: https://en.wikipedia.org/wiki/Scarf_joint
35. ### Engineering Frame Statics Problem

What makes you to think that way? Could you show us the FBD that you have done so far?
36. ### Pumping power calculation of a vertical closed-loop system

That difference of temperatures, if substantial and continuous due to good heat transfer on both halves of the loop, may help your pump. If most thermal energy does not remain in the fluid, something else is needed to stablish and keep a flow, overcoming friction and turbulence. There is phase...
37. ### Pumping power calculation of a vertical closed-loop system

Welcome @argeus ! Pumping required power depends only on fluid flow and pressure differential between inlet and outlet of the pump.
38. ### Engineering Frame Statics Problem

Note that support A is of a type that is unable to take horizontal loads. Link BD is working under compression, while link BE is working under tension. Therefore, there are two x-component forces acting on B in opposite directions.
39. ### Electronics Need help sealing my 775DC 30,000 rpm motor shaft

Yes, in centrifugal pumps, blowers and steam turbines, but not at those rpm's. Vibration and heat may be a problem in your application. Turbochargers for combustion engines spin very fast and need to be very carefully balanced. I don't believe that grease will help in your case. The above...
40. ### Flag orientation for a boat observer Vs a ground observer

In this case, the flag is simultaneously under the influence of two air streams, each having a different orientation and velocity respect to each other and the ground.
41. ### Flag orientation for a boat observer Vs a ground observer

Why are you trying to understand that? I see no mention about those observers in the problem text.
42. ### Electronics Need help sealing my 775DC 30,000 rpm motor shaft

Welcome, Mark! Research or look up "pump labyrinth seal 5 mm".
43. ### Engineering Stress-Strain question -- The maximum elastic elongation of a steel sample

Welcome, @menotu3169 ! Please, see: https://en.wikipedia.org/wiki/Poisson's_ratio
44. ### A pulley system with two pulleys and two suspended masses

Do you now understand how do they know those things? If not, please see: https://www.physicsforums.com/threads/i-e-irodov-problem-1-72-dynamics-problem-involving-a-pulley.991370/
45. ### Geometry: prove that point M is touched by 4 circles

Welcome, @Jiketz ! The relations shown at this link may help: https://en.wikipedia.org/wiki/Circumscribed_circle
46. ### How to obtain the orientation of a rocket wrt to ground with a 9-axis gyro?

What method of control will you use? Servos combined with thrust vectoring or fin angling?
47. ### I How to Calculate force exerted on a falling body?

Using an accelerometer would be the most precise test to perform. You can at least estimate a reasonable maximum distance the floor and body will deform during impact. Copied from https://en.wikipedia.org/wiki/G-force ”After a free fall from a height followed by deceleration over a distance...
48. ### Work to empty a tank

Another way to see it is the work or energy needed to move the whole mass of fluid between the height of its center of mass (full tank) and the height of the top of the tank.
49. ### Max speed of mass on war-wolf

Yes Or just for understanding the principle on which the system works, you could disregard the little mass. The little mass induces a CCW moment that is 24.5 times smaller than the CW moment that the big mass induces. Then, you have a mass oscillating about a pivot after being released from a...
50. ### Work to empty a tank

Perhaps the issue is that you have not considered the surface of the water to be 8 m above the floor or bottom of the tank and 2 m below the apex? I find this statement a little confusing: “empty the tank by pumping all of the water to the top of the tank.”