MythBusters Episode 135: Hidden Nasties
Air Date: December 16, 2009
It is feasible for a soda can to be contaminated with rat urine and subsequently transmit deadly viruses to humans.
busted
To create a control sample, Adam and Jamie spread out 1,000 aluminum soda cans, cleaned the top surfaces of the cans, and released 40 rats to walk on them for 90 minutes. Viewing the cans under a black light clearly showed that many of them became contaminated with rat urine. Next, they collected 1,000 cans from a variety of locations across San Francisco. Viewing these cans under a black light revealed that most of them also had organic substances on them, but it was not clear what those substances were. To find out what was on the cans, Adam and Jamie took swabbed samples to UC Berkeley, where a mass spectrometer was used to identify the chemical compounds. As expected, the control contained 15 proteins that indicated rat urine. However, the test sample did not contain any compounds indicating rat urine. Furthermore, a professor of epidemiology at UC Berkeley explained that any dangerous viruses contained in rat urine would not survive on the exposed tops of aluminum cans.
Many objects that people touch every day are dirtier than a toilet seat.
confirmed
Adam and Jamie chose a total of 8 objects to test for cleanliness: toilet seat, money, kitchen sponge, hotel room remote, computer keyboard, light switch, cell phone, and shopping cart. They swabbed each surface for 10 seconds and created Petri dishes from the swabs that incubated overnight. Their first method of measurement was to count the number of microorganism colonies on each dish. They found that the toilet seat sample actually had the fewest colonies, while the kitchen sponge sample had more than they could count:
- kitchen sponge (most colonies)
- money
- light switch
- computer keyboard
- hotel remote
- shopping cart
- cell phone
- toilet seat (fewest colonies)
However, they always wanted to account for the “nastiness” or harmfulness of the types of organisms on each Petri dish, so they had a microbiologist re-rank the samples. The list was as follows.
- kitchen sponge (most nasty)
- money
- light switch
- computer keyboard
- toilet seat
- cell phone
- shopping cart
- hotel remote (least nasty)
Finally, Adam and Jamie decided they needed a larger sample size to provide better results. They enlisted a group of biology students at UC Berkeley to collect more samples from the top five dirtiest surfaces. After collecting and analyzing these samples, the final list was as follows.
- kitchen sponge (most dirty)
- money
- computer keyboard
- toilet seat
- light switch (least dirty)
At 50 mph (80 kph), a sports car can launch off a small ramp and skip across a 100 ft (30 m) lake.
busted
To test this myth, Tory, Grant, and Jessi built dug a 100 ft trench at the end of a test track and filled it with water. They did not have the means to use a Lamborghini, as shown in the movie, but settled for a car of similar size and weight. They equipped the car to drive by remote control and drove it off a small ramp at 50 mph. Rather than skipping, the car hit nose-first and flipped end-over-end. Grant explained that the stunt in the movie was likely achieved with a platform just under the surface of the water and with weights in the car to keep it level.
(This myth came from the movie Cannonball.)
At high speeds, a sports car can skip across a 100 ft (30 m) lake.
confirmed
Tory, Grant, and Jessi again substituted an average car for a sports car, but equipped it with a nitrous oxide system to increase its top speed. Small scale tests showed that skipping worked better without a ramp, so no ramp was used for the full scale test. When the team drove the car onto the artificial lake, it skipped twice and continued driving on the other side.
the lambo engine is not mounted in the front of the car unlike the one used in the show, that has a major effect on why the front of the car dropped and the car flipped
December 17, 2009 at 12:29 AMThank you Eric. I have always enjoyed watching Mythbusters however they do make numerous mistakes. In this case, the mid mounting position of the Lamborghini engine. The episode even showed them removing the mid mounted engine from the Lamborghini model on the scale test. I am also surprised that they did not consider the depth of the water or the underpannel(skidplate) layout on any of the cars. They got lucky becuase the second car they tested with happened to be mid engine. It would be nice to see a little more accuracy in their tests.
December 17, 2009 at 2:18 AMEric and Frank, the MythBusters claimed that their test car had the same weight distribution as a Lamborghini – at least showing that they did consider this.
December 17, 2009 at 4:00 AMFor the car skipping across the water, if you look at the movie clip you can see that there is not an actual ramp. Rather, the road is elevated a little higher than the water. I think they need to revisit this and find the minimum speed needed to skip the car across the water without a ramp.
December 17, 2009 at 5:33 PMEric the full size cars they used were both fieros all production fiero were mid engine not front engine cars.
December 20, 2009 at 9:50 PMLove your show,theirs some guy’s that are trying to immitate but none even come close ,hope you guys keep me intertained for years to come,Thanks Guys and Kari-Really need to get her back My family never misses a show…
January 5, 2010 at 10:00 PMFirst, I wanted to say, I love your show and think you do an outstanding job!
January 12, 2010 at 11:27 AMIn the movie, there were no ramps used. If you look more carefully, there was a DIP! The dip dropped down then back up above the water level slightly. What that did was; when the car dropped down in the dip and started back up in that of short distance, it loaded the front springs on the car, to make it rise higher than the rear. When you make that happen it does not matter where the engine is located or how deep, the water is for the first few skips. Although, I am sure a rear mounted engine would be better but no skid plates
When it was re-enacted on TV, the ramp did not load the front springs as much as it did the rear, making it nose dive! I was watching the show almost yelling; that is not the way it was on the movie
Please watch this scene and consider trying it again
i would like to say hi and ive heard a myth that sound waves can make somthing float so i thought i would submit the myth and im australian
January 13, 2010 at 4:28 PMwill you use less gas if the tailgate is down on a pick-up truck while driving on the highway ?????
January 19, 2010 at 2:42 PMis time travel possible?
January 20, 2010 at 9:03 AMheyy myth busters,
January 21, 2010 at 9:11 PMi have a science fair project to do in a month and i have no idea what to do for it… can u help me out??
Love your show. The lengths you floks go to in order to satisfy your fans is awesom! Glad to see Miss Combs on the show. She IS a really good metal worker. When is Kari comiong back?
January 23, 2010 at 4:47 AMthey already did the tailgate down mileage myth several times.. turns out better mileage with the tailgate up.
February 9, 2010 at 1:49 AMI still think they should do this again….they flashed up a pretty weak diagram of the two cars. What I got from it, was that the cars weighed the same…they may have said “weight distribution” but I want a test with a rear heavy car and no ramp. And I hate how precise they are…I mean, if you have to go an extra 10 mph to get it to work, do it. Who cares if that is not what your “analysis of the film” found the speed to be.
March 24, 2010 at 9:36 PMto Sophie:
March 25, 2010 at 8:42 PMis time travel possible?
I am not trying to be a smartypants, but you are traveling throught time right now on the journey of your life. Maybe a better question to ask is, “Is Time Travel to the past or future possible?”
Hydroplaning is pretty simple, really.
March 28, 2010 at 7:49 AMIt’s almost entirely dependent on tire pressure. The square root of the tire pressure in PSI x 10 will give you the approximate speed in MPH that the tire will hydroplane. So a car with a typical tire pressure of 30 PSI will hydroplane at a speed of about 54 mph. At any speed below that it is going to penetrate the surface of the water.
At speeds above that it will hydroplane, but the impact of the tire on the water will dictate the speed at which hydroplaning will be supported. In short, the higher the vertical speed when contact is made, the faster you have to be going to sustain hydroplaning. This is down to the surface tension of the water contributing to hydroplaning. hitting the surface hard will break surface tension, taking it momentarily out of the equation.
I agree that the water skipping sports car needs to be revisited with no ramp. Hang on, was that not what the second test confirmed? Any road up. I consider the first test invalid in that the movie scene had no ramp, so it is irrelevant to bust a ramp version of the test. Sez-me.net
April 2, 2010 at 11:22 AMThe sound wave suspending objects suggestion from Michael, sounds (pun was unintentional) like the vibrating plate agitation of dust and sand experiment. Perhaps it looks like it is floating above the plate. Due to the vibration being so fast you do not see much of the plate hitting the sand particles momentarily. Possibly. A big loadspeaker with ball bearings or BB pellets might make some interesting patterns.
April 2, 2010 at 11:26 AMLooks like in the movie. I could be wrong , but it seems they have dug out a bit of land before the jump so the suspension and gravity were less of a concern. There’s is a slight dip that is long enough to let the gravity of the car to become lighter. Watch the dip as the car rises it the advantage of traveling not level but upwards with relaxed suspension. Since water is level this would be considered a small fall. What do you think?
April 21, 2010 at 8:54 PMSo the kitchen sponge was the most nasty but I’m curious, would the use of anti-bacterial soap make a difference in the results?
April 29, 2010 at 6:00 PMIn skipping the car the testers seemed to go about it the wrong way with the first car.
May 3, 2010 at 6:17 AM1 Did they examine the under side of a Lambo? I would think it would be much smoother and flater than production car they used. With the final test car they “Woke up ” by modifying the under side.
2 They mentioned that the test cars weight was the same as the Labmo but did not concider the rear to front weight comparison – I would think the Lambo rear weight to be front weight ratio would be much higher than the test car.
3 VW autoworks has a good point. Starting with a ramp was not a good idea – I could not see a ramp in the movie.
How do you scale weight, length (was 1:12 here), speed; how are the factors interrelated?
July 5, 2010 at 3:33 PMYou cannot scale gravity, so how do they do all this correctly so you get an accurate scaled down result?
The car that is in the film was mid engin and had a rea wing to drop the rea of the car down.
July 7, 2010 at 4:15 PMwhat type of car did they use in the car skipping myth?
July 24, 2010 at 4:16 PMToo many things wrong with this one… GRR!! The primary concern (NEVER addressed) is surface area vs. smoothness as skipping is an effect of surface tension far more than an effect of the whole “mass of displaced water pushing the car back up” explanation the show presented. Yes, that matters, but not nearly as much as the other considerations
July 24, 2010 at 4:46 PM1) The underside of a lambo chassis is purposefully smooth for aerodynamic effect. The Fiero, not so much.
2) While small scale models are cute, you cannot scale SPEED! Water resistance as tested is an effect of surface tension, which is affected by smoothness and area
3) Anyone who has ever jumped any vehicle will tell you that you can dramatically affect it’s flight characteristics with the throttle while in air. If Grant kept the throttle pinned after hitting the ramp, he quite likely did as much to case the car to nose over as any weight distribution. If he had coasted, or, better yet, been in neutral, it likely would have done better at keeping level.
i never would have guessd money would be that nasty.
July 30, 2010 at 1:30 PMthe lambo has the engine in the front but the car
July 30, 2010 at 4:21 PMhad its engine in the front caused the car to flip forward they need a car with a engine in the back and the myith could happen
Id like to point out that if u watch it in slow motion the car isn’t skipping on water in the movie. there are 2 land pieces in the water. the car bounces on land. It doesn’t skip. so u should remake the episode lol. see if a car can skip on land :p. cause the movie isn’t showing it skipping on water.
July 31, 2010 at 2:38 AMI agree with Zach who just ripped off my answer.
August 12, 2010 at 3:58 PMI think I even saw a small shrub on the island.
I expect then that the suspension was beefed up, because the car took off pretty quickly after the first bounce.
For the kitchen sponge I would like to know if there is a different result comparing a J-Cloth – cotton rag to the sponge and if you use hot water and dish sopt to rinse out the sponge does this remove azll tghe bacteria.
August 14, 2010 at 9:17 AM