How to stop a car without getting run over

CNBC
Updated
A team of eight rugby players were able to stop a fully powered Red Bull Formula One car. The physics prove the feat to be true.

You might have seen this video making the rounds on the Internet in the last couple of days. A team of rugby players holding back a fully powered Formula One car that's trying to run them over.

Before you keep reading. Watch the video first (it's short, promise) and then keep reading. We'll wait.

Okay...At first it seems unbelievable that a few men could pull off such a feat. Or maybe the video is a fake? Remember that Red Bull spends hundreds of millions dollars on its Formula One team, and billions in its overall marketing budget.

The Big Crunch wanted to know what was going on here, so we asked somebody who could tell us.

"The video is telling the truth," said Josh Browne. He's a former NASCAR engineer and crew chief. He has a Ph.D. in engineering from Columbia University, and is the co-founder of Pit Rho, a racing analytics software company.

He first had to remind viewers that the numbers in the video themselves didn't mean much. "Clearly Adrian Newey wasn't consulted on the ridiculous units stated in the video. But we should be able to figure this out," Browne said. "As Matt Damon would say [in the movie "The Martian" ], we should be able to science the s--t out of this one pretty easily."

"This just comes down to units conversion," he said. Here's how he broke it down for us:

Do you remember the equation for force from high school physics class? Force equals mass times acceleration, or F = ma for short. For the purposes of this exercise, we are going to use that. Here's the equation for the car's force.

If the mass = 800 kg (700 kg car + driver + 100 kg fuel), we need to find the acceleration. Let's assume it goes 0 to 100 km/h in 1.7 seconds, which means 100 km/h x 1000 m/km x 1h/3600s = 27.8 meters per second. That means a = 27.8 m/s / 1.7s = 16.4 m/s^2. "That's about 1.7 g-forces of acceleration, which seems reasonable for an F1 car," Browne said.

So the force of the car is 800 kg x 16.4 m/s^2 = 13,120 N (newton)

"Now we need to calculate the opposite force, the one coming from the scrum of eight rugby players. This will require some assumptions on our part, but we can do it," said Browne.

"These blokes are nonsensically strong," said Browne. Let's assume they can squat about two times their body weight. "If we use that bogus number from the video mentioning 831 kg as their collective body weight, that means each of the players weighs about 229 pounds."

For this activity, the acceleration "a" is gravity, as they move the mass perpendicular to the ground. "Now we can calculate an estimate for the applied force due to their squats," Browne said.

Force = 831 kg * 2 * 9.8 m/s^2 = 16,287 N (newton).

And now we have to add in the fact that the guys are pushing the sled at an angle. Call that angle 30 degrees, so then 16,287 times the cosine of 30 degrees is 14,100 N.

"14,100 N versus 13,120 N is pretty close, close enough anyway," said Browne. "It looked like the boys beat the car anyway, so I guess it's OK that this number is a tag higher."

After plugging all that in, "looks like these calculations back up the video. Tada!" But Browne made one final point:

"If they kept this up much longer though, my guess is that the boys would run out of 'gas' before the car does."