BUSTED: When food falls on the floor, it’s no longer safe to eat. Your best bet is to trash it or compost it. Even if a floor seems clean, it might be covered in microbes, living things too small to see. People can easily introduce harmful germs to a floor just by walking across it, says Donald Schaffner, who studies microbes. Eating certain microbes can make you sick.

Schaffner’s research has found that moist foods, like sliced fruit, pick up more germs than dry ones, like crackers. Hard floors transfer more microbes to food than carpet. But no matter the floor surface, germs can get on food in less than a second. Bottom line? There’s no safe amount of time for food to touch the floor, says Schaffner.

BUSTED: Food that falls on the floor is not safe to eat. Your best bet is to trash it. Or you can compost it. The floor may seem clean. But it might be covered in microbes. These living things are too small to see. Just walking across a floor leaves behind germs, says Donald Schaffner. He studies microbes. Eating some types can make you sick. 

Schaffner has found that some foods pick up more germs than others. More germs stick to moist foods like sliced fruit. Fewer germs stick to dry food like crackers. Hard floors pass more germs to food than carpet. Germs can get on food in less than a second. It doesn’t matter what type of floor they’re on. Bottom line? There’s no safe amount of time for food to touch the floor, says Schaffner.

 BUSTED: A bonk by a penny dropped from any skyscraper probably won’t do much damage. “There are two main forces that act on falling objects,” says Geoff Martindale. He’s an engineer who studies flight. “One is gravity, which pulls objects toward Earth,” he explains. “The other is drag, which slows objects down. Drag is caused by surrounding air particles pushing against an object.” When an object falls from a great height, the two forces eventually become balanced. The object stops going faster and falls at a constant speed.

The Empire State Building is a skyscraper in New York City that’s 1,250 feet (381 meters) tall. A penny dropped from its top floor reaches a top speed of 44 miles (70 kilometers) per hour. That’s about how fast it would go if you threw it hard. “Since a penny is so light, it would probably do little damage to a person at that speed,” Martindale says.

 BUSTED: A penny is dropped from a tall building. A person gets hit by it. This likely won’t do much harm. “There are two main forces that act on falling objects,” says Geoff Martindale. He’s an engineer. He studies flight. “One is gravity. It pulls objects toward Earth,” he says. “The other is drag. It slows objects down. Drag is caused by air pushing against an object.” These two forces balance out as an object falls. This balance causes the object to fall at a steady speed.

The Empire State Building is in New York City. The skyscraper is 1,250 feet (381 meters) tall. A person could drop a penny from its top floor. The coin would reach a speed of 44 miles (70 kilometers) per hour. That’s about as fast as a penny you threw hard. “A penny is so light. It would probably do little damage to a person at that speed,” says Martindale.

BUSTED: With a total length of 13,000 miles (21,000 kilometers), the Great Wall of China is one of the most impressive human-made structures on Earth. From 220 B.C. to 1644 A.D., China’s emperors had the wall built to protect their territory. But despite its size, this engineering marvel is difficult to see from space. Why? Its color and texture blend into the landscape.

Astronauts aboard the International Space Station—about 250 miles (400 km) above the ground—can only see the Great Wall with the help of a special camera.

Other human-made objects are easier to see from space. For example, China’s Three Gorges Dam can be seen with the naked eye. Its white color stands out against the blue water of the Yangtze (yang-see) River.

BUSTED: The Great Wall of China is 13,000 miles (21,000 kilometers) long. It’s an amazing site on Earth. China’s rulers built the wall hundreds of years ago. They built it from 220 B.C. to 1644 A.D. It was to protect their lands. The wall is huge. But it’s still hard to see from space. Why? Its color and texture blends into the landscape.

Astronauts live on the International Space Station. They’re about 250 miles (400 km) above Earth. They can see the Great Wall. But they need the help of a special camera. 

Other human-made objects are easier to see from space. One example is the Three Gorges Dam. It’s in China. The dam can be seen with the naked eye. It’s white against the blue water of the Yangtze (yang-see) River. So it stands out. 

BUSTED: This myth comes from the understanding that after you eat, your body sends some blood away from your muscles to your stomach. “The stomach needs extra blood to help digest food,” says Mark Chandler. He’s a doctor who treats children.

Doctors used to think that reduced blood flow to muscles could cause them to cramp, or become painfully tight. Doctors feared that could make it difficult to swim.

Now they know that there’s more than enough blood in your body—about 1.5 gallons (5.7 liters)—to safely digest food and swim at the same time. There’s no need to wait 30 minutes after a meal before jumping in. In fact, eating gives you energy to keep swimming!

BUSTED: You just ate. So your body sends some blood away from your muscles. It goes to your stomach. “The stomach needs extra blood to help digest food,” says Mark Chandler. He’s a doctor. He treats children. Doctors once thought muscles with less blood flow would cramp. That means to become painfully tight. Doctors feared that could make it hard to swim.

Now doctors know this isn’t true. A person’s body has about 1.5 gallons (5.7 liters) of blood. That’s plenty to digest food and swim at the same time. There’s no need to wait 30 minutes after a meal. Just jump in. Eating gives you energy to swim!

BUSTED: Swallowing a small wad of gum won’t do you any harm. Most gum is made of flavorings, sweeteners, and gum resin. This resin is a type of plastic that makes gum chewy. Our bodies can’t break down gum resin. So it passes through our digestive system.

“Gum leaves the stomach in less than two hours. It should come out in your stool, or poop, in a day or two,” says Chandler.

But take caution, gum chewers! Swallowing a lot of gum in a short time could be dangerous. “It’s possible a clump of gum could get stuck to your intestines,” he says. That would be a serious medical problem.

Your best bet? When you are all finished chewing, toss your gum in the trash, says Chandler.

BUSTED: Swallowing a small wad of gum won’t hurt you. Most gum is made of flavorings, sweeteners, and gum resin. This resin is a type of plastic. It makes gum chewy. Our bodies can’t break down gum resin. So it passes through our digestive system.

“Gum leaves the stomach in less than two hours. It should come out in your poop in a day or two,” says Chandler. But take caution, gum chewers! You don’t want to swallow a lot of gum in a short time. That could be risky. “It’s possible a clump of gum could get stuck to your intestines,” he says. That would be a serious medical issue.

Your best bet? Finish chewing your gum. Then toss it in the trash, says Chandler.