Can I compare a pedestrian being hit by a car to it falling from a certain height to the ground?

Let's say I want to teach kinetic and potential energy and I'd like to use an example that students can remember. The original idea is to show that speed (being squared) in the kinetic energy formula proves to be very important in the energy being delivered to a body. If a car travels in a 30 km/h limit zone with 34 km/h, how much more impact do those 4 extra km/h make when hitting a pedestrian (no braking)? You can compute the Joules difference but it doesn't say much on how it impacts the pedestrian. I thought about making this kinetic energy equal to the potential energy of a body falling to the ground and using the computed equivalent heights to show how much more dangerous it is. Is this a too simple model to be good enough?

• It's not as sexy as car on ped collisions, but the comparison is if I free-fall from 10 meters up, I go 10 m/s, but I need to go 41 meters up to get to 20 m/s, and I need to go 92 meters up to get to 30m/s. That graph should look a lot like a square root function. Change units as needed... – user121330 Jun 29 '17 at 18:11
• I'd like to go from a very practical and useful example of real life towards the theory so that most students can follow the logical association between the KE and PE. I hope it would be easy to remember because of the practical/emotional aspect. Elastic/Inelastic balls that collide and graphs I would leave for the second part where the students not interested in physics will probably space out. – MeDodo Jun 30 '17 at 8:54
• Knife penetration depth might be sexy enough... – user121330 Jun 30 '17 at 15:35