Determining the Static Coefficient of Friction between Tires and Snow

[@sankalpyadav2926]

Why is friction backwards in a car as car's tyre rotates backward for forward motion so friction between tyre and surface should be forward . But why isn't this true??

[@carultch]

If the force acting on a car while braking were acting forward on a car, your brakes wouldn't be doing their job. Instead, the brakes would be acting as a mysterious source of energy that does positive work on the car, if that were to happen. The purpose of the brakes is to slow down the car and get the road to apply a force that is opposite to the car's motion. Brakes work by squeezing a metal disk with a friction pad, and absorbing energy as the friction pad applies a kinetic friction force that acts against the metal disk's rotation. This causes your tires to push forward on the road, so that the road pushes backwards on the car. Yes, your tires are rotating forward, but the brakes are attempting to make them rotate at a speed that is slower than their current speed. The car's speed has to be consistent with the rotational speed of the tires, in order for the tires to roll without skidding on the road (so that you maintain your ability to steer). This causes the tires to push forward on the road, which then pushes backwards on the car.

[@johnshellenbergerteacher]

I'm a war veteran and engineer turned physics teacher. I teach in rural thailand but will be in bangkok soon. Your videos are well thought out and creative. I wish I could donate. I've been working in these poor public schools for too long. >1k per month!

[@FlippingPhysics]

John, know you are one of the reasons I make this videos and will do my best to always keep them free for everybody. Thank you so much for all the great work you are doing and please continue to use my videos to support that work! There are other things listed at flippingphysics.com/help-out.html which you can do to help me out that are not donating money. Thanks!

[@mateoagudelotoro4279]

How come this guy isn't a superstar on YT?

[@FlippingPhysics]

+Mateo Agudelo Toro Perhaps because people are more interested in watching dogs that are scared of fruit than educating themselves? kzbin.info/www/bejne/mYOWhKmCZ7igetE

[@1_in_8billion]

@@FlippingPhysics You'll always be a superstar to us FlippingPhysics

[@davefelix6519]

Awesome videos man! Really helping me out! You make it a whole lot easier

[@FlippingPhysics]

+Dave Felix "Makin' it a whole lot easier" is my middle name!

[@zhgshdbssss6536]

I didn’t understand the part when you said that the force applied is not on the car? Since it’s accelerating in that direction, there has to be a net force in that direction, right? If it’s just a matter of the inertia of rest then I should be able to conclude that even when we’re standing on the ground, there is no normal force, we’re not accelerating just due to the fact that we have inertia of rest, but that is incorrect obviously, so what is wrong with my reasoning?

[@jaymarch5592]

I'm sorry. "Summing the 🌲forest in the x-direction". Now all I can imagine is a cartoon wizard in a purple tie-die waving a wand a having an entire tree cover mountain side zooming across the country. I love it. Don't change a thing!

[@dj58]

oh man if I found your channel way back then may be I am not struggling in physics everytime I start to apply it on questions.

[@sahilbhairahish8927]

Please explain in detail ,your way to teaching is awesome ,i love to watch your video series

[@science1878]

what about the force applied by the brakes?

[@McTheWarhammer]

Is it funny that I just wrote a test couple hours ago with a very similar question? Loving your videos!

[@FlippingPhysics]

+TheWarhammer Yes, quite funny. Hopefully your students don't notice your comment?

[@McTheWarhammer]

Flipping Physics Well I was one the one taking the test, so I don't believe I have any students. And it's a good thing I remembered everyone brought mass to the party!

[@FlippingPhysics]

+TheWarhammer Ahhhh, I miss interpreted "wrote a test". I'm glad everybody brought mass to the party for you. Did you sing the song? (or at least dance a little?)

[@McTheWarhammer]

Flipping Physics As a matter of fact we did sing a little :).

[@FlippingPhysics]

+TheWarhammer That makes me happy.

[@megaxtay4687]

this man loves what he does

[@FlippingPhysics]

he does

[@alihussnain539]

Awesome.... Thanks Mr. P

[@Channel-dp3wc]

Could we also solve by energy and the work done by friction required to stop the car.

[@FlippingPhysics]

Yes, it would be very similar to this problem: www.flippingphysics.com/intro-wf-problem.html

[@Channel-dp3wc]

@@FlippingPhysics Thanks🙏 .

[@RickTrajan]

ey I need to watch all your videos to understand all these. but I think it would be well worth it.

[@FlippingPhysics]

It will be worth it.

[@ianholland6494]

This is great!

[@windthorpe9628]

5:31 hahaha "Everyone brought mass to the party"

[@prammar1951]

One of the best physics videos! Just s question, why g isn't negative 9.8m/s²?

[@yashkode818]

In that case we are just looking at the magnitude of acceleration due to gravity so direction wouldn't matter

[@saishiva8627]

i do not understand why you still have just 9k subs .u must be like running on like a 5million . no props on oct 2 2016 you would have that

[@mohamedbensalah7169]

Love ur videos man,, keep it up,, thank u

[@ismail4842]

Thank you so much great work please continue, you are superstar...

[@FlippingPhysics]

Thanks!

[@diyap7343]

Would there be a force applied if we were starting the car from rest and speeding up to a velocity, say, 20 m/s?

[@FlippingPhysics]

When you put your foot on the accelerator pedal of the car, it accelerates the car forward. (assuming you are in drive) This means there is a net force on the car in the forward direction. (Newon's Second Law) In a typical introductory physics class the forward force there would be a "force applied" by the engine on the car and the backward force (if we are not considering it to be negligible) is the force of friction caused by air resistance. The tricky part is that the engine does not actually cause a "force applied" on the car, it turns the wheels which interact with the ground and that interaction causes a force of static friction forward instead of that "force applied". In more advanced physics classes we would address the problem that way. (And it's kinetic friction if the wheels are slipping relative to the ground.) Does that help?

[@diyap7343]

@@FlippingPhysicsThat helps! Thank you Mr P

[@lucasm4299]

How isn't there an applied force Fa? Friction is pushing to the left. How can the car go to the right if there's nothing pushing it to the right? Maybe the motor is Fa.

[@FlippingPhysics]

Once the driver take their foot off the gas pedal, the inertia of the car keeps the car moving to the right. When you throw a ball, does it stop moving immediately when it leaves your hand, or does it keep moving?

[@tarbiyat4853]

thank you so much

[@techforagriculture2628]

Plz tell me how to find friction coefficient of tire on road

[@leonchirinda5338]

Same thing bro

[@FlippingPhysics]

That is exactly what this video does.

[@77katsumoto]

Was Billy's video project about Anti-Lock Brakes actually produced and uploaded to KZbin? It's not in the Newtonian Physics playlist and I couldn't find it anywhere with a quick search.

[@FlippingPhysics]

+77katsumoto I was wondering when someone would ask about that. The script has been written, all the video of the car and tires has been filmed and analyzed, currently Billy is waiting on a Flipping Physics Correspondent to finish up their part.

[@77katsumoto]

+Flipping Physics Ahh, I see!! I loved Bobby's solo video, so I am really looking forward to Billy's! By the way, I know enough people have already expressed how much your work is life changing, but I feel like you wouldn't mind reading it again: thank you for the awesome videos!! After 5 years studying human sciences in college, with the shy desire of one day becoming a physicist, your videos have boosted my inspiration to to pursue my dream! Even though we will, probably, never meet, I will always consider you my Physics Master! I will, also, always consider Billy, Bobby and Bo my precious classroom collegues and mentors! =]

[@FlippingPhysics]

+77katsumoto No, I definitely do not mind. Thank you for your kind words. I am proud to know you consider me your Physics Master and I will let Billy, Bobby and Bo know how you feel as well.

[@FlippingPhysics]

In case you guys missed it, Billy finally got around to completing his ABS Brakes video. www.flippingphysics.com/abs-brakes.html

[@Dragonpops]

Great video! for interest, what type of tires did you have for this test? Winter tyres or all seasons (M&S)?

[@FlippingPhysics]

I am pretty sure they were all season tires.

[@eleazaralmazan4089]

Great Video!

[@FlippingPhysics]

+Eleazar Almazan Thanks!

[@scienceseeker8377]

Please give me an answer why did we say there is no force applied .. i want to show to my teacher .. please type the full answer here and thanks in advanced

[@FlippingPhysics]

Actually, I explain why at 2:15. Why do you think there should be a force applied? What is pushing the car to cause this force applied?

[@scienceseeker8377]

@@FlippingPhysics So does that apply for every object or not ? Because I'm having difficulties understanding it .. I just thought because if the engine or something like that .. Can I have another question please? We have a problem that says a driver in a cars sees a cow in the road then skids to a stop and the brakes are locked .. Find the inital speed (no need to tell the values i want just to understand why my teacher did this) Here , our teacher typed this equation F = Ff (and typed the cofficent of sliding friction) I asked him why ? he Said because when the car skid to a stop , it was under 15 seconds until its stopped but i don't know what's the relation I'm really confused .. Btw I'm from Iraq and we study physics at school in English so could you please help me with the above issue ..

[@FlippingPhysics]

1) In this problem I am putting my foot on the brake which slows down the car. The engine is not pushing the car forward. Hence, no force applied. 2) Your second question is actually very similar to the problem in this video. The only difference is the known variables. The problem is solved the same way as this one.

[@scienceseeker8377]

@@FlippingPhysics I will tell you the problem from the book if you could solve it so i can show it to my teacher .. he sloves different from yours .. A driver sees a cow in the road ahead and applies the brakes so hard that they lock and the car skids to a stop in 24 m . If the road is concrete and it is a dry day , What was the car's speed when the brakes were applied ? The cofficent of sliding friction is 0.7 I'm very sorry for taking your time, this is the last comment

[@droneystyle]

AWESSSOME!!!!!!!!! :) Always thank you!

[@FlippingPhysics]

+Jinu Seol Again, you are always welcome.

[@frankthomas3550]

First time I've noticed that the socks are symmetrical.

[@simar2541]

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