Friday, October 04, 2013

The Problem with Physics


“A bullet is moving at a speed of 367 m/s when it embeds into a lump of moist clay. The bullet penetrates for a distance of 0.0621 m. Determine the acceleration of the bullet while moving into the clay. (Assume a uniform acceleration.)”

A physics teacher colleague of mine shared a problem he had with one of his students when it came to solving problems.  Rather than write out the problem in the form of a sum and throw in a relevant formula, they, the writers of the books or the tests, have put it into a story or a scenario like the one above.  One of his students wants to know more about the story than he does about the solution to the problem.

It does appear that there are a number of questions involved here…

Why is a man shooting at a lump of moist clay?  Do the police know he has a gun?  How big is the lump of clay?  Is it made into the shape of a person perhaps?  Is this some kind of target practice?  Does the clay man have a face?  Is it someone the shooter knows?  Someone he considers to be his enemy?  Is this all happening in a sound proof basement so that no one can hear?  How far away is he standing from the clay? Is the gun against the clay man’s temple execution style? Is he aiming between the eyes of the clay man?

What is the man thinking as he shoots the lump of clay? Is he angry about anything?  Is this a case of the last straw on the camel’s back? Does he think he will feel better if he shoots at the clay rather than shooting at the person who has made him angry?  Has he forgotten to take the medication which usually keeps him calm?

Has he thought about how he will dispose of the body?  Not the clay one – he can just dismantle that and make a few vases instead. No, the real body – the man he plans to shoot. Is he going to dig a shallow grave in the woods on the outskirts of town?  The river is too shallow this time of the year to throw the body in there.  Pity it’s not January when the thaw comes.

Does he just intend to stay at the crime scene holding the smoking gun until the police arrive? Is he going to go quietly? Can he afford a lawyer to defend him? He could show the police the empty pill bottle and tell them he has stopped taking his tablets.  Diminished responsibility shouldn’t be too hard to fake.

How will his mum take the news? It will break her heart.  She will ask herself a hundred questions beginning with “What did I do wrong?” She will stand by him, of course, as all mothers do.  Will she be strong at the trial or break down into tears?

Perhaps the image of his sobbing mother is too painful to imagine.  To continue with his plan is no longer appealing.  He takes the bullets out of the gun and wraps the gun in a piece of cloth.  He pulls out the loose brick in the basement wall and conceals the gun where he found it.

He makes a dozen vases in a variety of shapes and sizes with the clay.

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