Scenario: You are changing a car tire and need to use one of the 2 options below to exert force on the tire iron to loosen a tight lug nut (need the lug nut to spin counter clockwise, so toward the ground). Which option has the potential to create the most force in a single blow?

-the action is being performed by someone physically able to effectively perform both options mentioned below. -the tire iron can be set to whatever angle makes the most sense for each option (might make more sense to be parallel to the ground for option 1, but at a more acute angle for option 2).

Option 1: While standing on top of the tire iron, which is firmly covering the lug nut and setup to be parallel to the ground, jump straight up in the air and land on the tire iron while accelerating your feet in a downward motion.

Option 2: Instead of relying on your body weight falling, this option relies more on building/releasing energy like that of a proper baseball swing, a punch or certain karate kicks. For this option you setup the tire iron so the end of the handle, the end furthest away from where it actually hugs the lug nut, is angled down closer to the ground rather than completely parallel (to make the area on the tire iron we are attempting to strike more easily accessible). Then, facing the side of the car and standing a few feet left of the tire/tire iron, you side step towards the tire as fast as possible while attempting to create additional energy by picking up your right foot, leaning on your left foot, and then exploding towards the tire iron by pushing off your left foot and swinging your hips as much as possible. You transfer that energy with the completion of the kick/stomp with your right foot.

Option 1 seems like the 'common sense' answer, but I sometimes find your average person doesn't consider/acknowledge the amount of energy you can build up/transfer without the use of gravity. Since I don't have the means to calculate rough estimates myself I figured I'd ask for help here.



1 Answer 1


The answers to biomechanics questions like these are notoriously complicated. Basic physics often fails to account for all of the complex compressions and corrective actions which the human body does.

Option 1 seems like it will make sense because you will use as much of your muscular power as possible to get potential energy, and then apply it downward. However, with training option 2 starts to win out.

The reason has little to do with lugnuts and everything to deal with how the body manages itself. It will be harder to put your full force behind the effort in option 1. The reason is simple: you want to land. The tire iron is going to do something rather unpredictable to you (you don't know how much momentum it will take before the lug nut gives way). It also bends while doing so, meaning its forces are at an angle. It is very hard to suddenly correct after the lug nut gives way. Accordingly, your body will not be willing to put quite as much force into it. It will "pull its punch" (or pull its kick...) in order to stay upright.

In option 2, you have a stable foot on the ground which is in a position to deal with any lateral forces that arise during the strike. If the lug nut doesn't give at all (and thus the tire iron springs back at you and knocks you a little back), your left foot is ready to maintain your balance. If the lug nuts give suddenly, your right foot is already in position to land with a stable stance. Thus your body will be willing to apply more force.

An option 3 might be even more effective, striking from below. If you have the solid ground behind your back, you can push outward with all the force of a leg press. My leg press is much stronger than any dynamic exercise I can manage (though a trained individual may find otherwise).


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