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im doing a project that requires me to understand how cars move. from what I understand , its the friction that is creates in the tires that enables the tire to rotate, which then push the car forward. the velocity of the car also depends how much torque is generated by the axle that is connected to the wheel. what I don't understand is what do the brakes(drum or disk) do to the wheel that allow it to decrease its velocity. I know that when the brake pedal is pressed , it created friction within the tire to slow it down, but there is cases were the car still moves despite that the tires stop rotating. for sake of simplicity, im ignoring heat generated by the friction between the brake pads and wheel drum/disk, also neglecting air resistance.

at t=0, car is inputted with a certain v velocity. what I have to do is find the distance and time traveled, but I would also like to graph the rate at which the car deaccelerates depending on what type of brake it is used.

is there any good sources I can use to find to help me solve this? or could anyone describe what's going on in detail? ill clarify more if this doesn't make sense.

EDIT: the websites provided by the comments only focus on the first part of my question(which was very helpful thank you), but the second part still is not answered. the problem I have is understanding what does the brake due to wheel that allow it to deaccelerate(the whole car). since the torque created by the friction between the wheel and the surface is what causes it to move, do the brakes decrease the amount of friction created by the wheel and surface?


marked as duplicate by Gert, John Rennie homework-and-exercises Apr 22 at 11:09

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inside the brake assembly built into the end of each axle in the car there is a disc that rotates with the wheel and tire. Sitting next to the disc is a mechanism that pinches the rotating disc when you put your foot on the brake pedal. That pincher is bolted to the car so it cannot rotate when it pinches the disc. The pincher is made of material that generates lots of friction with the rotating disc when it pinches. In this way, pushing on the brake pedal creates friction on each disc, which acts to slow down the rotation of each wheel and tire- and bring the car to a stop.

  • $\begingroup$ so just to verify what im understanding, the engine provides a rotational force (or torque ) to an axle which then exerts that torque to the wheel. the brake pedal is pressed and this creates a frictional force that pushes brake pads against the wall of said rotating disk, which decrease the amount of wheel's torque which decrease the angular acceleration, which affects the angular velocity. and after all of that, the velocity of the car also decrease. is this correct on what im saying? $\endgroup$ – scremond Apr 21 at 22:08
  • $\begingroup$ yes, basically right. the engine produces torque to rotate the wheels in the direction of travel. the brakes produce torque that tends to slow the wheels down. $\endgroup$ – niels nielsen Apr 21 at 23:47
  • $\begingroup$ alright thanks! one more question, I found this website that describes another part of my project(its like an animation of sort that is interactive) scootle.edu.au/ec/viewing/L51/index.html# could you describe whats going on and why the car keeps on moving despite the wheels not having any rotational motion? $\endgroup$ – scremond Apr 22 at 0:01
  • $\begingroup$ no link to the website showed up! $\endgroup$ – niels nielsen Apr 22 at 0:02
  • $\begingroup$ I added the link in there, I clicked enter by accident $\endgroup$ – scremond Apr 22 at 0:04

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