Calculating the Braking Force of a Car

What determines how quickly a car can stop? How do tires and brakes affect braking distance? This video explains an equation that can be used to determine how well a car brakes.

Want to include factors such as rain or ABS no ABS? Here is how to alter the equation. In the original equation, multiply u (frictional coefficient) by acceleration, so the new equation reads:
D=0.5*V^2/(u*a)
Leave a as 1, and change u according to the condition.
With ABS ON: u can be considered 1, since ABS will attempt to maintain peak friction.
With ABS OFF: u will be less than 1, and will equal the frictional coefficient of a tire slipping on pavement.
With RAIN, and ABS ON: u will be less than 1, and will equal the frictional coefficient of a tire on wet pavement.
With RAIN, and ABS OFF: u will be less than 1 (and than with ABS ON), and will be equal to the frictional coefficient of a tire slipping on wet pavement. This is the worst case scenario of the four listed.

[niklutfi]

Hi, lets say that if the car are using 4 disc brakes with the same forces (no proportional valves installed), does that mean the total of F will be divided by 4?

[dineshkumarhariharan]

Simple and to the point. Very clear explanation with example. Helpful for my vehicle design..

[lacwaygarage]

This has helped me so much. I'm enjoying physics and mathematics in general a lot more as these concepts become more intuitive. Perhaps the narrator having an aussie accent similar to my own helps

[fairoozmunavar]

Thank you for giving a lesson about driving

[nicky]

This video helped a lot, cheers mate :)

[tomsalmon]

Interesting approach: I would have said, a= (90/3.6)^2/(2*100) = 6.25 m/s/s Then F=ma F=1600 * 6.25 = 10, 000 N

[JimM]

The mass is 1600kg, but you must also consider the rotating components of the car (gears, etc.). So you have to multiply mass by a factor γ (usually γ=1.05 for passenger cars). So equivalent mass should be 1600*1.05=1680kg..

[spencerosei]

quicker to use v2= u2 + 2as rearrange for acceleration and use f= m x a . ps a= v2-u2 / 2s therefore acceleration is -6.25 × 1600kg= -10000 N

[amareshpandey]

I have a dought ...that who done work friction between road and wheel or break

[pjv]

i dun understand why the velocity is taken as 25 instead of 90

[opufy]

I just had this in my final exam, i got so confused i got a terrible grade, only 43/60. I usually get 95s I was very disappointed with myself because it such a simple solution.

[dripgoku]

I'm an 8th grader that has this but it's so hard isn't this 10th-grade math. How did you get 5 x 10^5 and what is J 😭😭😭

[implick]

how would you then work out the mass of the car?

[meonjeo]

Can anyone solve this ?
Find the stoping distance if Vehicles weight = 300kg
Speed 40km/hr
Coefficient of friction of ground =0.8
Wheel dia= 566mm
Width =177mm
Consider all wheels

[infernohd]

What if they dont give a speed? What would you do?

[danteconciatori]

what type of force is this though? the normal force of the brake calipers on the disk?

[omkarnikam]

why haven't made a conversion of kg into N (Newton) because Joule means Newton × Metre and you haven't converted kg into Newton...

[memequeen]

What if I'm given the braking distance from a certain speed? How do I calculate the braking force? I'm so confused :(

[stuartcamp]

a car has an acceleration of 14m/s when a force of 32 kN is applied what is the mass of the car? That’s the question I need help with

[thilakshilaksman]

A Japanese bullet train has a mass of 715 000 kg and travels at a top speed of 275 km/h. Its braking distance from this speed is 4 km. Calculate the braking force. how do you do this