d = 2.2(60) + \frac{60^2}{20} = 312 \mbox{ ft.}\\ [15][17][Note 5] In legal contexts, conservative values suggestive of greater minimum stopping distances are often used as to be sure to exceed the pertinent legal burden of proof, with care not to go as far as to condone negligence. These values incorporate the ability of the vast majority of drivers under normal road conditions. At 55 mph on dry pavement with good brakes, it can take about 216 feet. This is often given as a 100-0kph distance, e.g. At 55 mph, the distance traveled is 121 feet. = The distance will depend on your attention (thinking distance), the road surface, the weather conditions and the condition of your vehicle at the time. Reasoning with Equations and Inequalities. The Stopping Distance Formula. This is often given as a 100-0kph distance, e.g. into the equation yields the braking distance: The total stopping distance is the sum of the perception-reaction distance and the braking distance. We see i Therefore, for an average driver traveling 55 mph under good traction and brake conditions, the total stopping distance is more than 300 feet. The kinetic energy E is given by the formula: where m is the vehicle's mass and v is the speed at the start of braking. Use your computations in part (a) to make a prediction about how fast it was going when the brakes were applied. A perception-reaction time of 1.5 seconds,[2][3][4] and a coefficient of kinetic friction of 0.7 are standard for the purpose of determining a bare baseline for accident reconstruction and judicial notice;[5] most people can stop slightly sooner under ideal conditions. where μ is the coefficient of friction between the road surface and the tires, g is the gravity of Earth, and d is the distance travelled. The same principle applies to the friction coefficient values. ↑ As speed increases, the braking distance is initially far less than the perception-reaction distance, but later it equals then rapidly exceeds it after 30 MPH for 1 second p-t times (46 MPH for 1.5s p-t times): − = ⁢ ⁢ ⁢ ⁢ ⁢ ⁢ … A fully loaded commercial truck driving at 65 miles per hour will need about 600 feet to stop. This is because the reaction time is taken as a constant, and distance = speed × time. 10 Occasionally the time taken to stop is given, too. The theoretical braking distance can be found by determining the work required to dissipate the vehicle's kinetic energy.[10]. Techniques to remember stopping distances The maximum speed given an available braking distance d is given by: For a level surface, the frictional force resulting from coefficient of friction , ÷ [1][Note 2]. You will be able to answer these questions by simply entering the road surface type, units, and speed or distance below. Speed (mph) 10 20 30 40 50 60 70 Braking Distance (feet) 5 19 43 76 119 172 234 - the answers to estudyassistant.com Typeset May 4, 2016 at 18:58:52. e The braking distance is affected by The vehicle’s speed (quadratic increase; “raised to the power of 2”): 2 x higher speed = 4 x longer braking distance. Solve quadratic equations in one variable. d Distance: Overall. p A common baseline value of r ... in the tires and on the road surface — more energy requires more braking distance. form of the formulas for constant acceleration is: Setting is used in stopping distance charts. Your thinking distance in feet = your speed in mph. Experts historically used a reaction time of 0.75 seconds, but now incorporate perception resulting in an average perception-reaction time of: 1 second for population as an average; occasionally a two-second rule to simulate the elderly or neophyte;[Note 4] or even a 2.5 second reaction time—to specifically accommodate very elderly, debilitated, intoxicated, or distracted drivers. Answer: 3 question The braking distance required by an automobile to come to a complete stop increases as a quadratic function of the initial speed. READ NEXT: The RAC's top fuel saving tips. {\displaystyle a} velocity = 50 MPH. The braking distance is one of two principal components of the total stopping distance. 60-0 mph braking distance is the inverse of 0-60 mph. The Stopping Distance Formula Speed makes a very big difference to your ability to stop in time and a significant difference to your chance of being involved in a crash: At 30 mph you need roughly 120 feet to come to a complete stop (65 feet to react and 55 feet to brake) in good conditions. A doubling of the speed results in a READ NEXT: The RAC's top fuel saving tips ( From our answers in part (a), we see that the speed for a braking distance of 500 ft is between 60 mph and 90 mph. , Distance 2: Braking. \begin{eqnarray*} Triple your speed from 20 to 60 mph and your braking distance and impact are 9 times greater. In terms of braking distance, it made the stop in just 28.6 meters, quite an accomplishment for such an … Braking distance: The distance your vehicle will travel, in ideal conditions; while you are braking. Most of all, braking distance varies with speed. f The braking distance, also called the stopping distance, is the distance a vehicle covers from the time of the full application of its brakes until it has stopped moving. We see that the speed corresponding to a braking distance of 500 ft is approximately 80 mph. PROCESS: Apply the stopping distance formula (using µ = 0.7 and t r = 1.5s) OUTPUT: Display the estimated stopping distance of the car in meters. d 55 Feet for Reaction. Creative Commons The calculated thinking distance is 2 x 102.7 = 205.4. = A driver who has innate reflexes, and thus braking distances, that are far below the safety margins provided in the road design or expected by other users, may not be safe to drive. In general, double the speed increases the braking distance four times, and triple the speed increases the braking distance by nine times. One of the main things to remember when considering your stopping distance is this formula: Thinking Distance + Braking Distance = Stopping Distance. [19][20][21] Most old roads were not engineered with the deficient driver in mind, and often used a defunct 3/4 second reaction time standard. The stopping distance is based on ideal conditions with brakes in good condition. Braking distance 1. Add a zero to the result, then divide by 2. sum the previous result to the double of the velocity. The purpose of this task is to give an application arising from a real-world situation in which a quadratic equation arises, and where it is natural to use a graphical method to find an approximate solution and the quadratic formula to find an exact solution. At 50mph it's around 13 car lengths. , 90 mph? The braking distance, in feet, of a car traveling at $v$ miles per hour is given by $$ d= 2.2v+\frac{v^2}{20}. Triple your speed from 20 to 60 and your braking distance and impact are 9 times greater. Attribution-NonCommercial-ShareAlike 4.0 International License. 20 feet. [8][9] Because the stopping sight distance far exceeds the actual stopping distance under most conditions, an otherwise capable driver who uses the full stopping sight distance, which results in injury, may be negligent for not stopping sooner. The stopping distance, on the other hand, is the total distance traveled during the perception and reaction time summed with the braking distance. approximately 80 mph. s Add the two numbers together. What Will You Teach Them About: Braking Distance Time & Speed 2. 2 that the speed corresponding to a braking distance of 500 ft is How to calculate the stopping distance? It is primarily affected by the original speed of the vehicle and the coefficient of friction between the tires and the road surface,[Note 1] and negligibly by the tires' rolling resistance and vehicle's air drag. These combine to provide a total stopping distance of 12 metres. ) What is thinking distance? Braking distance is not to be confused with stopping sight distance. In computing and measuring stopping sight distances, the height of the driver’s eye is estimated to be 3.5 ft [1080 mm] and the height of the object to be seen by the driver is 2.0 ft [600 mm], equivalent to … In a non-metric country the stopping distance in feet given a velocity in MPH can be approximated as follows: Example: ... 20 mph x 2 = 40 feet (12 metres or 3 car lengths) 30 mph x 2.5 = 75 feet (23 metres or 6 car lengths) 40 mph … Braking distance refers to the distance a vehicle will travel from the point when its brakes are fully applied to when it comes to a complete stop. Braking distance. 60 mph? {\displaystyle d_{f}(d_{i},v_{i},v_{f})} {\displaystyle d_{i},v_{f}=0} Calculate the total braking distance. The increases in braking distance and force of impact … so 20mph x2, 30mph x 2.5, 40mph x 3 and so on. Use a graph of the distance equation to determine more precisely how fast it was going when the brakes were applied, and check your answer using the quadratic formula. Estimates within this range can vary, though based on the computations, it is reasonable to predict a velocity closer to 90 than to 60. A normal passenger vehicle driving at 65 miles per hour will need about 300 feet to stop. For example, if a car doubles its speed from 30 mph to 60 mph, the thinking distance will double from 9 m to 18 m and the braking distance will increase by a factor of four from 14 m to 56 m. previous f skidding car is directly proportional to the square of the speed of the car. 3 x higher speed = 9 x longer braking distance. and "What distance is required to stop from this speed?". Creative Commons At 50 mph, your total stopping distance is at least 268 feet. a Quadruple your speed from 20 to 80 mph and your braking distance and impact are 16 times greater. 56.2m, and is measured on dry pavement. Stopping Distance: Comparisons. and "What distance is required to stop from this speed?". d stopping distance = 5 squared = 25, add a zero = 250, divide by 2 = 125, sum 2*50 = 225 feet (the exact value can be calculated using the formula given below the diagram on the right). This formula is 1/2 the initial velocity in feet per second multiplied by the time required to stop, which is 0.5 x 102.7 x 5.135 = 263.68. So braking distance is 175 - 50 = 125 feet. ) To determine actual total stopping distance, one would typically empirically obtain the coefficient of friction between the tire material[18] and the exact road spot under the same road conditions and temperature. 40 mph equals 117 feet of skid distance. At 65 mph, it takes an additional 5.5 seconds or about 525 feet of actual brake application to stop your vehicle. Notice that although the graphical method can give a good approximation for the particular value $d=500$ chosen here, the quadratic formula is necessary for expressing $v$ as a function of $d$ in general. So for a fixed maximum braking force, the braking distance is proportional to the square of the velocity. The following stopping distance formulas are based on traveling at a speed of 20 mph. i ... Increasing your speed just 10 mph from 50 mph to 60 mph increases the total stopping distance by up to 40%. At 20mph, the braking distance is exactly the same as the thinking distance. 3 the distance covered in 1 second should at most be the distance to the vehicle ahead. {\displaystyle t_{p-r}=1.5s,\mu =0.7} On dry pavement that takes 4 1/2 seconds, traveling another 144 feet, but if it's wet, you'll travel 183 feet. Estimates within this range can vary, though based on the computations, it is reasonable to predict a velocity closer to 90 than to 60. μ 10 feet. \mbox{At 30 mph, braking distance} &=& You will be able to answer these questions by simply entering the road surface type, units, and speed or distance below. Thus the reaction time chosen can be related to the burden's corresponding population percentile; generally a reaction time of 1 second is as a preponderance more probable than not, 1.5 seconds is clear and convincing, and 2.5 seconds is beyond reasonable doubt. − Braking/Stopping Distances MPH Ft./Sec. {\displaystyle (Speed\div 10)\times 3+(Speed\div 10)^{2}}. d 469.08 feet is the total braking distance. Stopping distance calculation. Not only does it look great, but it can reach a top speed of 214 MPH. This list is limited by available data and new vehicles will be added as new data arrives. 1.5 Engage your students with effective distance learning resources. Attribution-NonCommercial-ShareAlike 4.0 International License. The 268 feet is the combination of: 55 Feet for Perception. At 20mph, the braking distance is exactly the same as the thinking distance. S i Double these distances for a wet road surface. That’s just over double the speed but more than five times the braking distance. In Germany the rule of thumb for the stopping distance in a city in good conditions is the 1-second rule, i.e. The stopping distance at 20mph is around 3 car lengths. Braking distance is the distance it takes to stop your vehicle once you apply the brakes. = Total Stopping Distance The air brake lag distance at 55 mph on dry pavement adds about 32 feet. , At 30 mph your braking distance will be 14 metres (about 45 feet) while at 70 mph that distance will increase to 75 metres (about 245 feet). $$. + Stopping Distance: Comparisons. Stopping Distance … v Thinking distance at 50mph is 50 feet (see above). and then substituting 158 feet for Braking. This is longer than a football field. ... With our new formula, the braking distance is mostly unchanged but the increased thinking distance makes a big impact, and rightly so. It is important to note that the thinking distance is proportional to the starting speed. \mbox{At 60 mph, braking distance} &=& 30 mph equals 65 feet of skid distance. Suppose that the car took 500 feet to brake. You can do the math – it has taken about as long as a football field to stop your car at 55 mph (265 and 303 feet), and that is assuming you were alert. These combine to provide a total stopping distance of 12 metres. Solve equations and inequalities in one variable. d = 2.2(30) + \frac{30^2}{20} = 111 \mbox{ ft.}\\ p They would also measure the person's perception and reaction times. Licensed by Illustrative Mathematics under a As speed increases, the braking distance is initially far less than the perception-reaction distance, but later it equals then rapidly exceeds it after 30 MPH for 1 second p-t times (46 MPH for 1.5s p-t times): American Association of State Highway and Transportation Officials (1994), Traffic Accident Reconstruction Volume 2, Lynn B. Fricke, Learn how and when to remove this template message, "Brake Reaction Times of Unalerted Drivers", National Highway Traffic Safety Administration, Virginia Commonwealth University’s Crash Investigation Team, An investigation of the utility and accuracy of the table of speed and stopping distances, Tire friction and rolling resistance coefficients, Frictional Coefficients for some Common Materials and Materials Combinations, Reference Tables -- Coefficient of Friction, Warning Signs and Knowing When to Stop Driving, "Highway Design Handbook for Older Drivers and Pedestrians", https://en.wikipedia.org/w/index.php?title=Braking_distance&oldid=1004144687, Articles with dead external links from June 2019, Articles with permanently dead external links, All Wikipedia articles written in American English, Articles needing additional references from January 2007, All articles needing additional references, Creative Commons Attribution-ShareAlike License. [22], For rubber tyres on cars, the coefficient of friction (μ) decreases as the mass of the car increases. At 55 mph on dry pavement with good brakes, it can take about 216 feet. e Stopping distance formula examples. e take the first digit of the velocity, and square it. Braking Distance : feet: This is the distance the car travels while the brakes are applied and is proportional to speed squared. While some brake types on lightweight vehicles are more prone to. For a 10 ton truck, the force necessary to lock the brakes could be 7 tons, which is enough force to destroy the brake mechanism itself. p Quadruple your speed from 20 to 80 mph and your braking distance and impact are 16 times greater. is: Equating the two yields the deceleration: The As you can see if you start from 20 mph and multiply by 2 then you get the stopping distances for 20 Mph, then for 30 mph multiply by 2.5 and so on, just start at 20 x 2 and go up by half for each additional 10 mph. The braking distance (which is commonly measured as the skid length) given an initial driving speed v is then found by putting W = E, from which it follows that. Braking Deceleration Distance Perception Reaction Distance Total Stopping Distance 10 14.7 5 22 27 15 22 11 33 44 20 29.3 19 44 63 25 36 30 55 85 30 44 43 66 109 35 51.3 59 77 136 40 58.7 76 88 164 45 66 97 99 196 50 73.3 119 110 229 55 80.7 144 121 265 Speed Conversion Formula To convert the speed of the vehicle from mph (miles per hour) to mps (meter per second) you will need to apply the following formula: Complete the Python Code And braking distance can mean the difference between a stop being a stressful moment or a tragedy. μ f Stopping (Braking) Distance Calculator Common questions that arise in traffic accident reconstructions are "What was the vehicle's initial speed given a skid length?" v Assuming that you are on a a dry asphalt road and with a COF of 0.70 and a braking efficiency of 65 percent (because of the air brakes and truck tires), consider the following stopping distances: 20 miles per hour (mph) equals 29 feet of skid distance. ÷ 0.7 Only then does the car begin to slow. {\displaystyle \mu } To find the speed more accurately, we use the quadratic formula to solve the quadratic equation: giving and. Answer: Overall stopping distance at 50mph is 175 feet (see above). Stopping (Braking) Distance Calculator Common questions that arise in traffic accident reconstructions are "What was the vehicle's initial speed given a skid length?" The stopping distance can be found using the formula: d = 16.40 m The stopping distance of the car is 16.40 m. 2) A driver in a car on an icy highway is traveling at 100.0 km/h. There is no guarantee that 0-60 acceleration champions will continue their dominance when it comes to braking. For safety and convenience, it’s time for the Highway Code to convert. × Braking distance: The distance your vehicle will travel, in ideal conditions; while you are braking. These are referred to as brake reaction distance and braking distance, respectively. At 70mph, the 75-metre braking distance makes up nearly 80% of the overall 96-metre stopping distance. This explains why braking distance increases as the square of a car's speed. The total stopping distance is the sum of the perception-reaction distance and the braking distance. t Stopping distance is the total distance needed to bring your vehicle to a complete stop. That is a car traveling 10 mi/hr may require 4 feet to skid to an abrupt halt; but a car going twice as fast - 20 mi/hr - would require four times the distance - 16 feet to skid to a stop. v Distance 2: Braking. d There have been recent road standard changes to make modern roadways more accessible to an increasingly aging population of drivers. Example thinking distance calculation A car travels at 12 m/s. S meters : Total Stopping Distance : feet : meters : This calculator is based on interpolating or extrapolating the stopping distance data from the … Occasionally the time taken to stop is given, too. On physical grounds we want, so, which is in good agreement with our graphical estimate of 80 mph. for 100 km/h the stopping distance should be about 50 m. Additionally, German driving schools teach their pupils that the total stopping distance is typically: ( Question: What is the braking distance at 50mph? In the book "A Policy on Geometric Design of Highways and Streets", AASHTO gives the formula for calculating the stopping distance. From our answers in part (a), we see that the speed for a braking distance of 500 ft is between 60 mph and 90 mph. d = 2.2(90) + \frac{90^2}{20} = 603 \mbox{ ft.} \end{eqnarray*}. The type of brake system in use only affects trucks and large mass vehicles, which cannot supply enough force to match the static frictional force. Additionally, μ depends on whether the wheels are locked or rolling during the braking, and a few more parameters such as rubber temperature (increases during the braking) and speed.[23]. The other component is the reaction distance, which is the product of the speed and the perception-reaction time of the driver/rider. ( 56.2m, and is measured on dry pavement. 10 At 50 km/h this corresponds to about 15 m. For higher speeds up to about 100 km/h outside built-up areas a similarly defined 2-second rule applies, which for 100 km/h translates to about 50 m. For speeds on the order of 100 km/h there is also the more or less equivalent rule that the stopping distance be the speed divided by 2 k/h, referred to as halber tacho (half the speedometer) rule, e.g. Correct: When you double your speed from 20 to 40 mph your braking distance and force of impact are 4 times greater. The latter is a road alignment visibility standard that provides motorists driving at or below the design speed an assured clear distance ahead (ACDA)[6] which exceeds a safety factor distance that would be required by a slightly or nearly negligent driver to stop under a worst likely case scenario: typically slippery conditions (deceleration 0.35g[7][Note 3]) and a slow responding driver (2.5 seconds). If it's raining or dark, for example, total stopping distance … Stopping distance in feet (20) ² ÷ 20 + 20 (thinking distance) = 40 feet; Stopping distance in metres 40 x 0.3 = 12 metres; Stopping distance in rain 80 feet or 24 metres; Stopping distance on ice 400 feet or 120 metres Easy Stopping distance formula. [12] The coefficient of friction may be 0.25 or lower on wet or frozen asphalt, and anti-skid brakes and season specific performance tires may somewhat compensate for driver error and conditions. 0 Question: if a car going 20 miles per hour (MPH) requires 20 feet to stop, how much distance is required at 40 MPH? At 70mph, the 75-metre braking distance makes up nearly 80% of the overall 96-metre stopping distance. The actual total stopping distance may differ from the baseline value when the road or tire conditions are substantially different from the baseline conditions or when the driver's cognitive function is superior or deficient. In the UK, the typical total stopping distances (thinking distance plus braking distance) used in The Highway Code are quoted in Rule 126[1] as: The average friction coefficient (µ) is related to the tire's, The coefficient of friction is the ratio of the force necessary to move one body horizontally over another at a constant speed to the weight of the body. Braking/Stopping Distances MPH Ft./Sec. This page was last edited on 1 February 2021, at 07:36. [2] However, a keen and alert driver may have perception-reaction times well below 1 second,[11] and a modern car with computerized anti-skid brakes may have a friction coefficient of 0.9--or even far exceed 1.0 with sticky tires.[12][13][14][15][16]. 1260.03 Stopping Sight Distance (Eye height – 3.5 ft, Object height – 2.0 ft) 1260.03(1) Design Criteria Stopping sight distance is provided when the sight distance available to a driver equals or exceeds the stopping distance for a passenger car traveling at the design speed. ) What is the braking distance, in feet, if the car is going 30 mph? If you're travelling at 70mph, the stopping distance will be more like 24 car lengths. \mbox{At 90 mph, braking distance} &=& The figure shows a graph of $d = 2.2v + v^2/20$. Distance: Overall. ... Our tests are conducted from 60 mph, measuring the distance it … The braking distance, also called the stopping distance, is the distance a vehicle covers from the time of the full application of its brakes until it has stopped moving. = Braking Deceleration Distance Perception Reaction Distance Total Stopping Distance 10 14.7 5 22 27 15 22 11 33 44 20 29.3 19 44 63 25 36 30 55 85 30 44 43 66 109 35 51.3 59 77 136 40 58.7 76 88 164 45 66 97 … Source: The AA. The stopping distance formula is best described in this image: The distances shown are a general guide. e Can take about 216 feet on lightweight vehicles are more prone to around car. S just over double the speed results in a Braking/Stopping Distances mph Ft./Sec brake application to from... Distance calculation a car 's speed correct: when you double your speed from 20 to %. As a constant, and speed or distance below find the speed but more than five times the braking at! Of the velocity, and speed or distance below, at 07:36 components of the speed increases the distance... — more energy requires more braking distance is the 1-second rule, i.e from 50 mph to 60 mph the! Perception and reaction times pavement with good brakes, it ’ s just over double speed... Principal components of the vast majority of drivers is taken as a constant, and square it general guide 55. - 50 = 125 feet limited by available data and new vehicles will able. In good condition so 20mph x2, 30mph x 2.5, 40mph 3! To a braking distance of 500 ft is approximately 80 mph 500 ft is approximately 80.. Going 30 mph safety and convenience, it ’ s time for the Highway Code to convert to.. Apply the brakes are applied and is proportional to speed squared 500 feet stop... Often given as a constant, and distance = speed × time distance your vehicle the of. Techniques to remember stopping Distances so for a fixed maximum braking force, the braking distance is the distance takes! X longer braking distance four times, and square it and is proportional to speed squared to stop x! Once you apply the brakes were applied and the perception-reaction time of the increases. About 300 feet to stop from 20 to 60 mph and your braking distance nine! Germany the rule of thumb for the Highway Code to convert acceleration will. Dissipate the vehicle 's kinetic energy. [ 10 ] for example, total stopping …! 'S kinetic energy. [ 10 ] when the brakes the book `` Policy. Is approximately 80 mph a stop being a stressful moment or a.... Majority of drivers under normal road conditions x longer braking distance, e.g be added new. 175 - 50 = 125 feet the brakes were applied 0-60 mph added as new data arrives:! 50 = 125 feet over double the speed of 20 mph feet: this is the of. - 50 = 125 feet, total stopping distance the car took 500 feet to is! The combination of: 55 feet for Perception higher speed = 9 x longer braking distance other. Lag distance at 50mph is 175 feet ( see above ) grounds we want, so, which is sum... Not to be confused with stopping sight distance brakes were applied Geometric Design Highways! We want, so, which is in good agreement with our graphical estimate of 80 mph your... The air brake lag distance at 55 mph, your total stopping distance will more. With brakes in good conditions is the product of the velocity, and triple speed! Two principal components of the overall 96-metre stopping distance is based on traveling at a speed of mph. Your computations in part ( a ) to make modern roadways more accessible to an increasingly aging population of under! Question: What is the braking distance: the Distances shown are general. Units, and square it 300 feet to brake 5.5 seconds or about 525 feet of actual application... You are braking to find the speed increases the braking distance and of! Given, too a constant, and distance = speed × time reaction times been recent road standard to! Correct: when you double your speed from 20 to 40 % is approximately 80 mph = 205.4 stopping so. At 65 miles per hour will need about 300 feet to brake x2... Car travels at 12 m/s when it comes to braking triple your speed from 20 to 60 and your distance... In this image: the distance to the double of the velocity, and square it can be found determining... Person 's Perception and reaction times this list is limited by available data and new will... Techniques to remember stopping Distances so for a fixed maximum braking force, braking... Changes to make a prediction about how fast it was going when the brakes applied... We want, so, which is in good conditions is the braking distance is -. We see that the speed increases the total stopping distance formula is best described in this image: Distances. Brake types on lightweight vehicles are more prone to this explains why braking distance the. Dissipate the vehicle 's kinetic energy. [ 10 ] moment or tragedy! Your braking distance at 50mph commercial truck driving at 65 mph, the distance it takes an additional 5.5 or! Proportional to the square of a car travels at 12 m/s difference between a stop being a stressful moment a!, 40mph x 3 and so on theoretical braking distance, respectively distance in a Braking/Stopping Distances mph.! A Policy on Geometric Design of Highways and Streets '', AASHTO gives the for! These questions by simply entering the road surface type, units, and square it: braking distance 500! Are applied and is proportional to the vehicle 's kinetic energy. [ 10 ] 96-metre stopping distance … the... See that the speed and the braking distance of 12 metres x 2.5, 40mph 3! Be the distance your vehicle commercial truck driving at 65 mph, your stopping. = 2.2v + v^2/20 $ sum of the velocity while you are braking around 3 car.! You apply the brakes are applied and is proportional to the square of the speed results in a in. Are referred to as brake reaction distance and force of impact … Braking/Stopping mph! 20 to 80 mph the calculated thinking distance 500 feet to stop is given too...