Questions tagged [friction]
The friction tag has no usage guidance.
104
questions
0
votes
1answer
44 views
Inconsistant load cell readings - (static) fiction perhaps?
First off I'm not an engineer so please excuse the simple language I use to explain my question!
I have an arrangement whereby I have a steel plate suspended from basically a bridge. The plate is free ...
0
votes
0answers
29 views
Cases in finding the maximum weight of the block
I am dealing with this problem about belt and dry friction. I need to find the maximum allowable weight of block B to maintain static equilibrium. I have given value of weight of the block A. The line ...
0
votes
1answer
26 views
Friction in Wedges: finding the mass of the block C on the verge of slipping
I need to solve for the mass of block C that is in the verge of slipping. All surfaces have a coefficient of static friction of 0.11. The cable connecting the wedge B and C is parallel with the ...
2
votes
1answer
52 views
Determine the minimum horizontal force to disturb the equilibrium
Three blocks of 1N 2N and 3N are placed one over the other respectively. If the friction between the topmost 1N and the middle 2N block is twice the friction between the lowest 3N and floor then ...
0
votes
3answers
54 views
How to guess direction of friction in any case
Here , in case of a death well situation as an example.
Q How is direction of friction going to be opposite to mg or in upwards direction ?
Why not:
In case of like circular turning , direction of ...
2
votes
2answers
84 views
Effects of rolling resistance on wheel angular and vehicle longitudinal speed
The differential equation for wheel speed can be given as:
In here, $T_t$ is driving torque (not braking), $F_x$ is longitudinal force of tyre, $J_w$ is wheel inertia, $\dot{w}$ is angular speed of ...
0
votes
2answers
39 views
Find minimum horizontal force required to keep the block and wedge stationary?
In the adjoining figure, the coefficient of friction between wedge (of mass M) and block (of mass m) is μ. Find the minimum horizontal force F required to keep the block stationary with respect to ...
0
votes
1answer
37 views
Are there any frictionless objects or is it possible to create frictionless objects?
In the latest StarTalk NDT says that without friction space crafts would not be able to slow down when reentering orbit. The friction against the air slows it down from 17,000 miles per hour down.
...
7
votes
2answers
459 views
Wheelbarrow minimize wear
I have a question about the design principle. To explain my problem I made the sketch "wheelbarrow". To minimize wear, which design is preferred?
0
votes
1answer
31 views
For cleaning food and objects, power scrubber vs. electric rotary toothbrush?
I'm asking about cleaning produce like potatoes and melons, NOT human organs here. This handheld power scrubber
looks like your average rotary toothbrush! Indubitably I know that a toothbrush's brush ...
0
votes
1answer
37 views
A quantity to measure whether brakes should be repaired
Suppose you can record some suitable parameters each time a driver uses the brakes of a vehicle (assume it's a heavy truck if necessary). Is there a reasonable formula for a dimensionless quantity $Q$ ...
1
vote
1answer
72 views
Jamming & linear guiding
For a linear guiding I need to know the concept and understand the jamming limits. See picture. If I choose concept 1 or concept 2, what will be the value of X? How can I calculate this?
2
votes
2answers
61 views
Forces acting on a weightless member
A weightless bar is pinned at the top of a triangle with N weight. Both rests at the horizontal plane.
There is a horizontal force F acting on the weightless bar, and a given coefficient of friction μ ...
1
vote
1answer
41 views
Pressure drop in a CFD simulation of an air flow too small
I am simulating a turbulent air flow through a rectangular channel with the goal to match measured velocity profiles and the static pressure at certain points. My problem is that the pressure drop in ...
-1
votes
1answer
38 views
Required force to start the motion of a leaning bar
A uniform bar weighing 343N leans on a heightened plane (see figure). What force P is needed to start the bar moving?
Coefficient of friction (on all surfaces) = 0.30
The blurred length is most ...
1
vote
0answers
32 views
Force necessary to resist motion due to torque on a drum brake
A drum is subjected to a counterclockwise torque of 16 in-lb. What horizontal force is necessary to resist motion?
Coefficient of friction = 0.40
Weight is neglected.
I'm having a hard time on this ...
1
vote
1answer
48 views
Find frictional losses as box exits ramp
I have a box traveling on a ramp just before the ramp levels out. At this point all values are known:
I want to calculate the frictional losses from this point to when the box is completely off the ...
2
votes
1answer
32 views
Friction versus ratcheting pawl
We are working to design a lock mechanism and need to hold a square plunger out of a hole for extended periods of time (potentially years). The square plunger is under pressure from springs to return ...
2
votes
2answers
220 views
How to add friction to a rope without using abrasion
I have a pay-out winch. It is a spool of rope that has a disk brake attached to it, so I can control the torque required to rotate the spool. When the torque is very large, however, the rope begins ...
2
votes
1answer
117 views
Calculating Bending Force on a Fixed Metal Plate
At work we've had a steel pipe support break on us, and I can't for the life of me figure out what happened. Here's some background info:
A long (125m) steel heating pipe (ø51mm) is suspended, resting ...
1
vote
2answers
263 views
Disc Brakes - Swept Area , why is larger better?
I am trying to understand why a bigger swept area on disc brakes provides higher braking force for the same force being exerted on the brake lever/pedal by the rider.
If we use the same exact brake ...
5
votes
3answers
1k views
Why is the friction factor in laminar flow independent of pipe roughness?
The Darcy friction factor is defined as:
$$f_D =\frac{64}{Re}$$
with $Re$ I mean Reynolds number (global).
I was wondering why Darcy in laminaire flow is independent of pipe roughness (wall roughness)?...
2
votes
2answers
94 views
Acceleration of spool on conveyor belt
A spool has a mass of 500 kg and a giration radius of $k_G = 1.30m$. The
spool lies on the surface of a conveyor belt, the static coefficient of friction is $\mu_S=0.5$.
The spool is not moving at ...
1
vote
0answers
31 views
Where do I learn about jewel bearings?
I would like to take a deep dive into the world of jewel sourced watchmaking components (including, but not limited to, bearings) but I am having trouble finding any textbooks on the subject. Are ...
0
votes
1answer
33 views
How is forward motion initiated in this case?
Source:byjus.com
Do these forces cancel out each other? If yes, how is forward motion initiated?
Also, in this situation, since friction between the road and the wheels is enabling motion, which ...
1
vote
1answer
46 views
How does the friction on the front and rear wheels of a car vary?
Consider a Rear-Wheel Driven car. The questions refer to friction between the wheels and the road.
1.Direction of friction on the front and rear wheels when car accelerates? Is it static or kinetic?
...
-1
votes
3answers
39 views
Need help regarding working of drum brakes
I was learning about the working of drum brakes, and I came to know, that each of the two brake linings of drum brake apply horizontal force in opposite directions.
That confused me, because, if ...
2
votes
1answer
48 views
Why Does Particle Size Matter For Bridge Pillars here?
I was watching this engineering video here and it talks about a technique used to prevent the pillars of a bridge from falling over in an earthquake. The pillars of the bridge are partially submerged ...
1
vote
1answer
41 views
clamp force or torque for non-steel screws - brass or aluminum
It is common for screw tightening to have the relationship between torque and clamp force defined by:
$$T=kFD$$
However, all the calculators seem to assume the screw is steel. How can this be ...
0
votes
0answers
20 views
Train decelerations in no power condition
Suppose a train is running at 30kmph and suddenly the power is switched off. How do we calculate the reducing velocity at intervals and what factors will affect the change in it?. Further how much ...
1
vote
0answers
30 views
Bevel gear friction and inertia calculation
I want to calculate the friction and inertia between 2 bevel gears with straight teeth.
I know how to calculate those parameters between regular gears with straight teeth.
Is there any difference for ...
1
vote
1answer
31 views
Inertia and friction between gears
I have a question regarding inertia and friction between gears.
I have a gear which is connected to the rod at one end and an electric motor which is connected to the other end. I know the torque of ...
1
vote
1answer
115 views
Hydraulic Brakes - Why motorcycle brakes more powerful than bicycle brakes?
I was wondering why motorcycle brakes have so much more stopping power than bicycle hydraulic brakes (Than can be found on mountain bikes for example).
The rotor has a bigger size which gives better ...
4
votes
1answer
407 views
Calculate max deceleration without front wheel slipping (bicycle)
I am trying to calculate the maximum braking force/deceleration for a bicycle.
Note: the question assumes only the front brake is used
Free body diagram:
Typo: in the image above, "$F_{a,\ max(...
0
votes
1answer
20 views
Formula for finding the optimal weight for a given torque and vice versa
Whenever i see videos of two trucks pitting with each other to see who has a stronger, i always see comments that sounds like:
If you load the other truck more it would beat the other one
That truck ...
-1
votes
1answer
40 views
What is the average energy loss due to rolling friction in contemporary motor vehicles?
Around what percent of energy provided by gasoline is lost as heat due to rolling friction in vehicles? Is this number higher for larger vehicles likes trucks than smaller vehicles like bikes?
...
-1
votes
1answer
32 views
What is the minimum frictional force required for a vehicle to operate smoothly, retain traction, and prevent any skids?
I am not looking for a specific number of course. I know that it may perhaps vary with different vehicles. However, I'm trying to figure out how to theoretically calculate the minimum necessary ...
1
vote
2answers
173 views
What is the exact concept of bearings?
Mechanics books always highlight that the main advantage of bearings is to reduce friction, especially when we talk about them in rotational motion applications. The example of ball bearings is always ...
0
votes
1answer
116 views
Calculating optimal angle on a rolling pulley wheel, which holds weight, on a horizontal cable
The 40 kg load on the rope accelerates from 0 to 50km / h in 6 seconds.
The rope is tightened with a force of 500kg while the whole assembly is on it.
The middle pulley is driven by a dc motor.
I ...
2
votes
0answers
439 views
how to calculate required torque and rpm to through a 160 gram cricket ball horizontally at 160km/h velocity?
I am going to design a bowling machine. In this design, I'm going to use two motors that are being placed vertically and their shaft are attached with two horizontal identical wheels with a space of ...
0
votes
2answers
105 views
Faster car drifting (motorsport) when using limited slip vs welded differential
I have been drifting RWD (rear wheel drive) cars for some years now. I tend to think about every engineering solution that other drivers use and how does it work before applying it to my car.
What ...
2
votes
3answers
461 views
Why is the Bush of a motor not replaced with a ball bearing?
Ball bearing reduces friction to a large extent than sliding friction. Motors use a metal ring called bush which slides against the shaft when the shaft is rotating. If a force is exerted on the shaft ...
0
votes
0answers
28 views
What type of bearing should I use to allow a ring to rotate around a fixed axle
What type of bearing should I use to allow a ring to rotate around a fixed axle. Axle is horizontal.
The rings inner diameter can be flush with the stationary rod or have a gap as needed. What type ...
0
votes
1answer
107 views
Friction factor for wormgear design materials
I'm working on a database which involves geometric design parameters, forces analysis and efficiency and losses for wormgear reduction design systems.
To determine the tangential and axial forces ...
0
votes
2answers
103 views
How to calculate traction force w.r.t. rotational speed of a shaft mounted at a certain angle on a surface?
I am designing a new mobile robot platform and i need a generic solution for the robot in order to establish a proper mathematical modeling. My question is about calculation of the traction force of ...
2
votes
3answers
249 views
Dead mans brake on a hand-pushed wheelchair
Would it be possible to install a dead-mans brake on a wheelchair?
I have been calling around and wheelchairs do not seem to come with a dead-mans brake. With that i mean the brake found on airport ...
1
vote
1answer
102 views
Pacejka “Magic Formula” tire models origin of the name
It might be a little off topic but I'm trying to find source for why is that model called magic formula? I read that it's a simple function of commonplace functions, a data fitting. Is it simply an ...
0
votes
2answers
127 views
Refute my assumption: Bearings Don't Improve Efficiency
If two surfaces rub together with a normal force between them, friction is generated. You could add lubrication between those two surfaces and reduce that friction.
Bearings essentially consist of ...
2
votes
2answers
50 views
How to keep lighting “barn doors” open
I have two alum plates (45cm x 20cm x 1mm) that are hinged on the long side with two 30 x 80 hinges (30 x 40 each tang) in the middle, and "L" bracket / 20mm brace at the ends secured with a M4 loc ...
1
vote
2answers
168 views
What are fluids or “goos” called, that increase friction?
I have a shaft inside a bushing, the shaft has a gear on one end that is supposed to provide resistance to other gears it is driven with.
I'm having a hard time finding the correct term for the sort ...
