Questions tagged [friction]

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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 ...
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29 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 ...
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1answer
34 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. ...
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2answers
456 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?
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1answer
30 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 ...
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1answer
36 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 $Q$ ...
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1answer
49 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?
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2answers
54 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 ...
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1answer
29 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 ...
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1answer
35 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 ...
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0answers
31 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 ...
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1answer
40 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 ...
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1answer
27 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 ...
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2answers
214 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 ...
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1answer
87 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 ...
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2answers
196 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 ...
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3answers
922 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)?...
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2answers
85 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 ...
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0answers
30 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 ...
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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 ...
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1answer
42 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? ...
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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 ...
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1answer
46 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 ...
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1answer
32 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 ...
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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 ...
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0answers
29 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 ...
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1answer
30 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 ...
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1answer
108 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 ...
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1answer
339 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: For dry tarmac where I know there is enough ...
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1answer
19 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 ...
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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? ...
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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 ...
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2answers
170 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 ...
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1answer
102 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 ...
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0answers
379 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 ...
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2answers
95 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 ...
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3answers
391 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 ...
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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 ...
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1answer
106 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 ...
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2answers
97 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 ...
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3answers
243 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 ...
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1answer
99 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 ...
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2answers
125 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 ...
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2answers
49 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 ...
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2answers
156 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 ...
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2answers
67 views

Which design to maximize friction for a device standing on concrete?

I have a device 4cm X 5cm X 15cm that stands on asphalt/concrete/road. So, the device is taller than its base which makes contact with the asphalt. I want to maximize the friction so that the device ...
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1answer
90 views

Effect of friction (or horizontal motion) on vertical surface deformation

I am trying to model the dynamics of some system. In summary, the system consists of one horizontal linear actuator that drives an object along a planar surface and one vertical actuator that brings ...
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1answer
57 views

How do you calculate the chain tension required when compressing bulk material over a conveyor?

Bulk material is conveyed over a slat conveyor, and the material is leveled with overhead rollers while being transported in the conveyor to maintain an even material height. Most of these "levelers" ...
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1answer
128 views

Minimum required rolling friction between pulley and the rope

The 40 kg weight accelerates and runs on a rope from 0 to 50 km/h in 10 seconds. I want to calculate the minimum required rolling friction that I need (acceleration without slipping) to achieve ...
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0answers
54 views

Regarding the ITTC Guidelines for Ship CFD applications

I was reading through the ITTC – Recommended Procedures and Guidelines - Practical Guidelines for Ship CFD Applications (https://ittc.info/media/4196/75-03-02-03.pdf) document and this little thing ...