How does kinetic energy affect stopping distance of a vehicle traveling at 30 miles per hours compared to the same vehicle traveling 60 miles per hour

This post will be quite simple. We’ll work with only 1 equation here to show you the effects of increasing our speed from 30 mph to 60 mph in relation to braking. The energy in question is Kinetic Energy (J), or energy that’s in motion. Since our car is moving, it has a certain amount of kinetic energy. But just how much? And how does it compare/matter when looking at the effects of braking/hitting something. We’ll be using two variables here; Mass (kg) and Velocity (m/s):

Kinetic Energy (J) =

A basic physics equation, KE = mv2/2 where we square Velocity, then multiply that by Mass and then divide by 2 to get our Kinetic Energy.

The focus of this post is the (Velocity) 2. Our Velocity is squared, no matter how slow/fast we’re going, so our Kinetic Energy will also end up being exponential, not linear. When our speed is doubled, our Kinetic Energy is quadroupled here. If you can imagine the graph, it would be a parabola starting at the origin, and curving upwards.

So lets start plugging in numbers. For reference, we’ll use a 3,000 pound car at speeds of 30 mph and 60 mph. We’ll first need to convert our Imperial weight to Metric, which equals to approximately 1361 kgs. Then convert our Imperial speed of 30 mph to Metric, which equals to approximately 13.4 m/s. Now we plug everything in:

Kinetic Energy (J) =

Kinetic Energy (J) ≈ 122,000 Joules