ASK YOUR SCIENCE TEACHER by Larry Scheckel

This week’s question was asked by a friend.

QUESTION: How come when you toss a ball in the air while sitting in your car, it comes right back into your hands, and what about when you throw it out the window?

ANSWER: Suppose you’re sitting in your car, holding a ball in your hands and going down the highway at 50 miles per hour. Both you and the ball are also moving forward down the highway at 50 mph. When you toss the ball straight up in the air, the ball is still moving forward at 50 mph-same as you and the car. You find the ball lands right back in your hand.

The phenomena is consistent with Newton’s First Law of Motion; An object in motion tends to stay in motion. During the time the ball was in the air, it was moving forward at the same speed as the “tossee” and the car.

Someone watching the ball and car from the side, say a farmer out standing in his field (there’s a pun here), would see the ball follow the path of an arc. In math, it’s called a parabola. But the ball-tossing person in the car would see the ball go straight up and straight down, no matter if he were moving or the car was stationary on the roadway. Einstein said all motion is relative. It depends on one’s frame of reference or point of view.

Now if the person tosses the ball sideways out the window, another force acts on the ball- the force of air resistance or air friction. The ball would land somewhat behind the point it was dropped. Drag is another term used for air resistance.

If you and the car were moving in a vacuum, where there is no air, the ball tossed out the window would land on the roadway at a point directly below the point of release. Alas, such a happening could not occur, as both you and the car need air to breathe.

Same thing would happen when you jump up in a plane traveling at 600 miles per hour. You land in the same place instead of flying backward and smacking into the back of the airplane.

What about tossing a bomb out of an airplane? This whole scenario wraps itself around the nature of precision bombing, the attempt to hit a target on the ground while causing minimal damage to the surroundings. It’s the idea of limiting collateral damage.

The technology was not available to do precision bombing in World War I. It was a different story 20 years later in World War II as the United States Air Force believed that heavy bombers could hit targets from high altitude using the newly invented Norden bombsight.

The Norden bombsight was a top-secret development early in World War II. A crude analog computer tracked the bomber’s ground speed and direction, altitude, wind and temperature. The Norden system was tied to the plane’s autopilot that guided the plane when on the bombing run.

In practice runs in the United States, bomber crews claimed they could “drop a bomb in a pickle barrel.” In aerial combat over the skies of Europe, it was a different story. Bad weather over the target, German fighter planes, anti-aircraft guns and limited training for new crews made for a pretty big pickle barrel.

One could argue that real precision bombing first occurred in May 1972, when laser-guided bombs dropped by F-4 Phantoms destroyed two bridges in North Vietnam.

The Gulf War, starting on January 16, 1991, witnessed extensive use of precision-guided “smart bombs” and missiles. It was the first time in history that such precision weaponry played a decisive part in war. Civilian casualties were kept to a minimum. The 40-day aerial campaign paved the way for the 4-day ground war.

“There never was a good war, or bad peace,” penned Ben Franklin. Fortunately, the Gulf War did not entail the massive loss of civilian lives that had occurred in World War II. In the war on terror waged in the past two decades, smart weapons, including drones, are a large part of our arsenal.

Send questions and comments to: lscheckel@charter.net.

Larry Scheckel is a retired Tomah High School physics teacher.

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Steve Rundio is editor of the Tomah Journal. Contact him at 608-374-7785.

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