Brakes Definition and 85 Threads

A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.

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  1. H

    Maximum Force Applied to Brakes

    Homework Statement Suppose you are driving a light weight pickup truck, and it takes 15m of stopping distance to stop when you are traveling 5 m/s, using max. force from the brakes. 1. Suppose you really load up the truck, so that the mass of the loaded truck is twice that of the unloaded...
  2. T

    Conservation of momentum - Brakes

    Not sure where to post this as it isn't actually homework, all variables are made up. Homework Statement A car, weighing 1000kg and moving at 3m/s puts it's breaks on and slows down to a stop. What happens to the momentum? Homework Equations p=mv The Attempt at a Solution...
  3. F

    How to measure temperature of brakes in F1 cars?

    How do they do it? They need to know this to determine optimum braking temperature in order to have best performance braking. Yet, how do they do it? Measure it optically?
  4. I

    Slowing a Car from 25mi/hr to Stop in 2s: How Long?

    the brakes of a car can slow it down from 60 mi/hr to 40mi/hr in 2 s. how long will it take to bring the car to a stop from an initial velocity of 25 mi/hr at the same acceleration?
  5. P

    Derivation for Friction in Brakes

    Homework Statement Derive the expression for frictional resistances in block brakes.Use standard symbols to denote required parameters. Homework Equations The Attempt at a Solution My actual problem is the fact that I have checked 2 reference books, both have derived the...
  6. S

    Car accelerates then brakes. What is its displacement?

    Homework Statement A car starts from rest and travels for 5.5 s with a uniform acceleration of +1.4 m/s2. The driver then applies the brakes, causing a uniform acceleration of -1.9 m/s2. The breaks are applied for 1.70 s. (a) How fast is the car going at the end of the braking period? 4.47...
  7. R

    If she hits the brakes, how far will she travel before stopping?

    Homework Statement A person driving her car at 56 km/h approaches an intersection just as the traffic light turns yellow. She knows that the yellow light lasts only 2.0 s before turning to red, and she is 30 m away from the near side of the intersection (Fig. 2-29). Should she try to stop, or...
  8. B

    Truck brakes and the distance they travel

    Homework Statement Truck brakes can fail if they get too hot. In some mountainous areas, ramps of loose gravel are constructed to stop runaway trucks that have lost their brakes. The combination of a slight upward slope and a large coefficient of friction in the gravel brings the truck...
  9. D

    Change of temperature in disc brakes

    Homework Statement Basically I've got a brake system which i have designed, and i need to calculate if the brake fluid will overheat if the vehicle brakes from its top speed to a halt, and if so at what speed (or how long after braking commences) they will overheat Brake force = 13000N...
  10. D

    Formula for deceleration, using a parachute and wheel brakes

    Homework Statement Basically i need to find the braking distance and time for the deceleration of a vehicle for the following conditions, using a parachute using a parachute, and wheel brakes does anyone know of a suitable formula to calculate this? Homework Equations...
  11. W

    HELP car brakes to stop before cliff how do you find work

    A car and driver weighing 5710 N passes a sign station (bridge out in 23.1 m) She slams on her brakes and the car decelerates at a constant rate of 9.94 m/s^2. Accel of grav is 9.8 m/s^2. What is the ganitude of work done, stopping the car before it falls. We don't know how to do it at all...
  12. S

    Calculating Thermal Energy Dissipated from Brakes on a Descending Car

    Homework Statement Proper design of automobile braking systems must account for heat buildup under heaving braking. Calculate the thermal energy dissipated from brakes in a 1260-kg car that descends a 18.5° hill. The car begins braking when its speed is 102 km/h and slows down to a speed of 34...
  13. K

    The difference between rear and front brakes of a bicycle

    Hi, I'm a sophomore student at Arizona State University studying Aerospace. I'm currently taking my first physics class ever and I'm loving it. Although there isn't enough calculus, it's mostly formula based, so it's a bit disappointing on that end. Anyways, ever since I started taking the...
  14. B

    Thermal Energy dissapated from brakes.

    This is another one that I have given several attempts. Calculate the thermal energy dissipated from brakes in a 1600 kg car that descends a 20 degree hill. The car begins braking when its speed is 95 km/h and slows to a speed of 30 km/h in a distance of 0.27 km measured along the road. I...
  15. B

    Calculating Cable Car's Speed on Hill Descent - 4122N Braking Force

    Homework Statement The 2100kg cable car shown in the figure descends a 200-m-high hill. In addition to its brakes, the cable car controls its speed by pulling an 1840kg counterweight up the other side of the hill. The rolling friction of both the cable car and the counterweight are negligible...
  16. O

    How far are you from the intersection when you begin to apply the brakes?

    Homework Statement You are diving to the grocery store at 20 m/s. You are 110 m from an intersection when the traffic light turns red. Assume that your reaction time is 0.70 s and that your car brakes with constant acceleration. A) How far are you from the intersection when you begin to...
  17. mtworkowski@o

    Troubleshooting Anti-Lock Brakes on 04 Dakota | Expert Tips

    When mine kick in it's like I'm sliding on ice. I'm pulling the fuse. Is there something wrong with them or do they just work badly by design? 04 Dakota.
  18. M

    Increase the efficiency of brakes in an ATV?

    how can we increase the efficiency of brakes in an ATV specially? I'm working on an ATV these days n plan to use disc brakes... i read about cross-linked braking circuit...can someone tell me how efficient is this system...should i try to employ it?iv heard it has been used in Audi before...can...
  19. D

    Friction Brakes Ergometer: Novel Application

    Dear All. I am working on a uni project building an ergometer for an MRI machine. I was interested in purchasing a disk brake system to control the resistance and the power output for the ergometer. The application requires that all parts to be non magnetic as it will be used in an MRI...
  20. D

    Friction Brakes Ergometer: Novel Application

    Dear All. I am working on a uni project building an ergometer for an MRI machine. I was interested in purchasing a disk brake system to control the resistance and the power output for the ergometer. The application requires that all parts to be non magnetic as it will be used in an MRI...
  21. D

    Friction Brakes Ergometer: Novel Application

    Dear All. I am working on a uni project building an ergometer for an MRI machine. I was interested in purchasing a disk brake system to control the resistance and the power output for the ergometer. The application requires that all parts to be non magnetic as it will be used in an MRI...
  22. C

    Exploring the Possibility of Brakes on the Drive Shaft: A Discussion

    Brakes on Drive Shaft ?? HI all, I am new to this forum. I have a doubt on braking system. Any help in this regard is highly appreciated. Why can not we have brake on drive shaft or some point at flywheel ?? Any discussion in this regard is appreciated. I am hoping to find a...
  23. J

    What Was the Speed of the Car Based on Skid Marks and Kinetic Friction?

    Homework Statement You have been called to testify as an expert witness in a trial involving an automobile accident. The posted speed limit was 70 km/h . The driver of the car slammed on his brakes, locking the wheels, and left skid marks as the car skidded to a halt. You measure the length...
  24. E

    Question on centrifugal brakes

    hey guys, i was wondering if any of you know the general values for the friction coefficient as well as the mass of the brake shoes and the spring constant for the centrifugal brakes (i know there are probably all sort of values, but please just give me a general rough estimate)? The brake is...
  25. C

    Train Braking Distance Calculation

    Hi. I would really appreciate it if someone could please help me with the following M1 level kinematics question as I am really stuck. The brakes of a train can produce a retardation of 1.7 m/s^2. If the train is traveling at 100 km/h and applies its brakes what distance does it travel...
  26. C

    Coefficient of static friction with brakes

    On a level road with its brakes on, the shortest distance in which a car traveling with 83 km/hr can stop is 95 m. This shortest distance occurs when the driver uses anti-lock brakes which means that the car brakes without skidding. What is the coefficient of static friction between the...
  27. B

    Advantages/disadvantages of disc brakes in any vehicle

    could someone let me know the problems being faced while using disc brakes in any sort of vehicles?
  28. B

    Help Finding Info on Braking Systems Co. - Retro-Fit Magnetic Brakes

    Has anyone heard of this company? I'm told they build retro-fit magnetic braking systems for roller-coasters etc. but all I have is the name and I can't find a website. Any help is much appreciated.
  29. Z

    Safer: Braking with or without Skidding?

    Safer to skid or not? I think I got the question right, I am just not sure if I had covered all aspects of the problem (unfortunately, my textbook doesn't have answers). Homework Statement Is it safer to slam the brakes (therefore locking the wheel) and skidding to a stop OR is it safer...
  30. K

    Calculating Vehicle Distance: Kinematics Question on Brakes

    Hi, can someone please check if this is right? A driver applies brakes on seeing a traffic signal 400m ahead. At the time of applying the brakes, the vehicle was moving with 15m/s and retarding with 0.3m/s^2. What is the distance of the vehicle from the traffic light after 1 minute? x =...
  31. E

    Constant acceleration and brakes

    how would i do this problem... You are driving to the grocery store at 20 m/s. You are 110 m from an intersection when the traffic light turns red. Assume that your reaction time is 0.50 s and that your car brakes with constant acceleration. 1)How far are you from the intersection when you...
  32. S

    Coefficient of Friction of brakes

    You are driving a 2500.0-kg car at a constant speed of 14.0 m/s along an icy, but straight and level road. While approaching a traffic light, it turns red. You slam on the brakes. Your wheels lock, the tires begin skidding, and the car slides to a halt in a distance of 25.0 m. What is the...
  33. S

    Why Does a Car Behave Erratically When Its Back Brakes Are Locked?

    I just recently registered with this website and it is incredible! I can't believe how great it is. I stumbled upon here looking for help with a physics question my professor posed to us. If a car is coating down a hill and locks its front brakes, it will travel in a reasonably straight...
  34. C

    Do disk brakes resist being pulled out?

    When two pads squeeze a moving rotor with thousands of pounds of force in a disk brake, the friction resists the rotation of the disk enough to slow a car. How much resistance (if any) does the squeezing of the pads provide if you try to pull the moving rotor out at roughly 90 degrees...
  35. K

    Solving a Problem: Car Speed When Driver Slammed Brakes

    I'm a bit confused as to how to finish this problem: At an accident scene on a level road, inestigators measure a car's skid marks to be 88 m long. It was a rainy day and the coefficient of friction was estimated to be .42. Use these data to determine the speed of the car when the driver...
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