The Physics of Stopping: Mercedes Commercial 80 mph in 4 Sec

[krehbester]

There's a Mercedes commercial that claims one of their cars can stop from 80 mph in 4 seconds. My question is: if you stop any object moving at 80 mph in 4 seconds will it always take the same distance to stop no matter the size or weight? If so how far?

 

[russ_watters]

If they give you the time and speed, the size and weight are already accounted for.

80mph is 117 fps. Assuming constant deceleration, the average speed is 58.7fps and therefore the distance is 235 ft.

The primary factor in stopping distance is the friction coefficient of the tires/ground. In this case, to decelerate by 20mph every second, you need a friction coefficient of .95, as g is 21 mph/s.

 

[sir-pinski]

The physics of stopping an object in motion is determined by several factors, including the initial velocity, the mass of the object, and the force applied to stop it. In the case of the Mercedes commercial, the car's ability to stop from 80 mph in 4 seconds is likely due to its advanced braking system and powerful engine.

However, the distance it takes to stop an object moving at 80 mph in 4 seconds will not always be the same, regardless of the object's size or weight. This is because the force required to stop an object is directly proportional to its mass, according to Newton's second law of motion (F=ma). Therefore, a heavier object would require more force to stop it in the same amount of time compared to a lighter object.

Additionally, the distance it takes to stop an object also depends on the friction between the object and the surface it is traveling on. For example, a car traveling on a wet road will take longer to stop compared to the same car on a dry road, due to the decrease in friction.

Therefore, it is not possible to determine a specific distance that it would take to stop an object moving at 80 mph in 4 seconds, as it would depend on the specific circumstances and variables involved. However, it can be said that a more massive object would require a longer distance to stop compared to a lighter object, all other factors being equal.