Engineering Stack Exchange
Engineering Stack Exchange

Questions tagged [friction]

151 questions
5
votes
1 answer

Quantifying and measuring friction under extreme conditions

I want to quantify friction between a bullet and barrel to test different friction-proofing coatings and treatments. Is there a controlled test I could do at low speeds in a lab between samples of treated copper and steel that would be theoretically…
feetwet
  • 1,757
  • 2
  • 15
  • 41
2
votes
2 answers

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 to bury itself into the rope that is still on the…
John Henckel
  • 123
  • 4
1
vote
1 answer

Apply constant load to an electric motor - low tech way

I want to know how much I can over-drive a small electric motor. Its speed at the rated voltage is too slow, so I want to find a higher voltage that won't blow it. It will only be used intermittently, but I figure if I run it for 100x the max…
Jodes
  • 1,304
  • 1
  • 12
  • 34
1
vote
1 answer

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 head can be far gentler than the power…
user24573
0
votes
2 answers

Can a 2 HP motor move a 1,000 lbs flat-bottom boat across a flat material surface?

There is a small 13' long x 6' wide, 1,000 lbs (total weight of everything) all-fiberglass white pontoon boat with dual flat-bottom fiberglass pontoons. (Each flat pontoon bottom is 2' in width, with an empty 2' space between the two, running the…
Bill D.
  • 1
0
votes
1 answer

Pivot Point with Low Friction

Inspired by this question, I am looking for a low-friction pivot for a clock pendulum. The design uses magnetic repulsion to keep the pendulum going. A magnet is attached to the bottom of the pendulum and a coil is fixed just below it. My pivot now…
Mattman944
  • 101
  • 5
0
votes
1 answer

How to stop a leg from sliding?

One of the legs of a bed is bent (I believe it buckled). The bent can be corrected to be straight, however under the application of load to the bed, the leg will slowly return to the bent position. My goal is to fix the leg in place and stop it from…
tryst with freedom
  • 111
  • 6
0
votes
2 answers

Smallest possible rolling resistance

So, question is how to achieve the lowest possible friction in a scenario where there is a steel bar rotating AGAINST the circular frame at high rpm. Now, when it comes to sliding friction lowest coefficient of friction is hard steel against greased…
Nix
  • 1
  • 2
0
votes
3 answers

Rack on rack vertical force

I have a locking mechanism in mind, that is made with two racks. Rack 1 is fixed and then we push down rack 2 to lock something. After that a horizontal force is applied to rack 2. I calculated the resulting vertical force as shown in the sketch. I…
Grega
  • 33
  • 5
0
votes
1 answer

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. There have been animals that have been found to…
1.21 gigawatts
  • 237
  • 2
  • 10
0
votes
0 answers

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 time will it take to stop from that position and the…
Kapil Makker
  • 1
-1
votes
1 answer

Sumo-bot Wheel Help - Sticky tires or Wide & less friction tires?

I am building a sumo-bot and our competitors have thin sticky tires, while we have wider and less sticky tires. The diameter is the same, and the gearbox/motor is the same. Who will win? PS: Sticky tires: https://www.pololu.com/product/694 & wide…
MathBunny
  • 1
-1
votes
1 answer

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 probably 5m. I've done several revisions on answering…
KDGH
  • 33
  • 4