Wednesday, September 1, 2004
This is an archived issue and therefore not the current one. For the current issue, click here.
Crazy Lab Shenanigans!
Newton's Laws of Motion (in the lab!)
First Law of Motion: "Every body continues in its state of rest or of uniform speed in a straight line unless acted on by a nonzero net force."
- A serological pipet will continue to suck up matter until it is full, it explodes, it unhooks somehow, or the absent-minded researcher notices it and takes his finger off the suction button.
- A lab tech who falls asleep at a table will remain asleep until her supervisor yells "WAKE UP!"
- You drop a test tube onto the lab bench. It will continue to roll across the bench until the friction from the bench slows it to a complete stop. Either that, or it will just roll right off the lab bench.
- The test tube slips off the lab bench. It will continue to fall until either you catch it or it hits the floor.
Second Law of Motion: "The acceleration of an object is directly proportional to the net force acting on it and is inversely proportional to its mass. The direction of the acceleration is in the direction of the net force acting on the object."(ΣF = ma)
- A lab tech slips a 1mL centrifuge tube into the centrifuge. She turns it on, and the tube accelerates until the centrifuge is spinning at the set speed. Since the tube has such a small mass, there is not a lot of force even with such high acceleration.
- A test tube falling at 9.80 meters per second squared with a mass of 1.30 grams has a net force of ~0.13 Newtons. Whether it breaks upon landing is another story.
Third Law of Motion: "Whenever one object exerts a force on a second object, the second exerts an equal and opposite force on the first."
- The aforementioned falling test tube lands on the floor with a force of ~0.13 Newtons. Therefore, the floor exerts ~0.13 Newtons right back onto the tube. It breaks. Clean it up.
- Your finger exerts a force on a very small unseen shard of the broken test tube you are cleaning up. It exerts the same force back on your finger. It penetrates your skin, and now you're bleeding!
- Fearing more blood-letting mishaps, you decide to take a short break. You sit on a wheeled desk chair, position your feet against the wall, and push off it. The force you exert on the wall will return the same force on you, sending you and the desk chair rolling across the room.
- As the chair scoots across the floor, you crash into the glass disposal box and knock it over. You fall off the chair and, upon landing, exert a force on the floor which returns the same force onto you. You are bruised.
- When you landed, some broken glass that had fallen out of the glass disposal box lay scattered on the floor, and you landed on it, exerted a force onto the glass which in turn exerted the same force onto you. Now you have significantly more cuts.
- After briefly considering changing careers, you finally go home, deciding it must just be a bad day. You feel much better after your teeth exert a force that is equaled by a mouthful of a nice hot meal.
- Several months later, you submit your completed report to Science. This action has the equal and opposite reaction of a "we regret to inform you..." letter. Or maybe you'll be in the lucky one percent and receive a "we are pleased to inform you..." letter! You didn't endure cuts, scrapes, bruises, broken glassware expenses, infections, and stitches for nothing!
Wow! Sir Isaac Newton was a genius!
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