This is the kind of video that might suffice as standalone weekend entertainment. After all, braking a truck with your feet is a pretty demonstrably bad idea. But the lovable nerds at Popular Science just had to take it a step further and work out the physics of trying to halt a truck ala Fred Flintstone, noting
Let’s estimate he can push down with a force about a quarter of his weight. If he weighs 200 pounds, this would result in a force of 50 pounds, or 225 N. We also know that the force of friction (F) between his feet and the asphalt depends on the force with which he pushes down (N) and the “coefficient of kinetic friction”(μ) between the soles of his shoes, which we will assume are made of rubber, and the pavement.
F = μN
The μ between rubber and asphalt varies between 0.5 and 0.8. Let’s assume a value of 0.7. Therefore, solving for stopping distance, we get:
D = ½(2100kg)(18m/s)2/(0.7)(225N) = 2160 meters, or over 1.3 miles!
The situation might be improved if he exerted his full 200 pounds, or 900 Newtons, of force against the ground. In that case:
D = 1/2(2100kg)(18m/s)2/(0.7)(900N) = 540 meters (about a third of a mile)
However, the amount of torque exerted on his ankles and knees might make that a problematic proposition.
Surf on over to PopSci for the entire breakdown (no pun intended).