Murphy's Corner

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The following extra credit writing assignments were created by senior physics major Mike Murphy.  You will get 2 points extra credit for each assignment that is handed in.  Please write one or two paragraphs on each of the following topics.  Please hand in a copy of the assignment with your answer.  You may choose to draw an illustration to help your explanation, but you must still write at least one full paragraph for each scenario.  Please do not confuse Murphy's Corner with Murphy's Law.

Two writing assignments on Newton’s Third Law to be completed before exam 1.

1. You are driving down the highway on a clear sunny day, when suddenly a small fly meets its doom on your windshield.  As you have learned, according to Newton’s Third Law, the force of the fly hitting your windshield is equal to the force the windshield applies to the fly.  However, this may seem strange since the effect of the windshield on the fly seems much more dramatic than the effect of the fly on the windshield.  Please explain this difference in outcomes given Newton’s Third Law.  Hint: According to Newton’s second law, how will their accelerations compare?

2. Your music teacher has asked you to help move a piano from the classroom onto the stage.  You push hard on the piano and it begins to move, slowly at first, but then a little faster, and a little faster.  Based on Newton’s Third Law, you know that the force you use to push the piano is equal to the force of the piano pushing back on you.  In light of these equal and opposite forces, explain how the piano can move at all, let alone accelerate.  Hint: Think of Newton’s First and Second Laws when describing the situation. 

Writing Assignments on Impulse & Momentum - most helpful when handed in before test 2.

Please write one or two paragraphs on each of the following topics.  You may choose to draw an illustration to help your explanation, but you must still write at least one full paragraph for each scenario. 

1. After coming home from a long physics class, you decide to dive on your nice fluffy couch and relax.  Explain why jumping on the couch is a better, and less painful idea than diving onto the hardwood floor. Be sure to think in terms of momentum, impulse, and force when describing the situation.

2. At a family picnic you are invited to join in an egg toss contest.  You and your partner are given a raw egg to toss back and forth.  After each successful toss you take a step further away from your partner.  Any pair that breaks their egg is out.  As the distance between you and your partner increases, the task becomes more difficult.  You notice that when catching the egg, you place your arms out in front of you with your hands palms up to receive the egg, and as you catch it, you move your hands down and to your side, slowing the egg to a stop safely.  Other groups attempt to catch the egg by holding their hands straight out in front of them, palms facing forward like a baseball catcher.  However, when the egg hits the motionless hands it splatters on contact.  Why is your method of catching the egg less likely to break the egg than the baseball catcher method?  Again, be sure to think in terms of momentum, impulse, and force when describing the two methods.

Writing Assignments on Current in a Simple Circuit- most helpful when handed in before test3

Please write one or two paragraphs on each of the following topics.  You may choose to draw an illustration to help your explanation, but you must still write at least one full paragraph for each scenario. 

1. You have been asked to wire a sign for Joe’s Diner.  Each letter in the sign is lit by a collection of light bulbs with the whole circuit powered by a battery.  You first begin to wire the bulbs in series, but notice that as you add each light bulb all the bulbs are dimmer than before.  In one or two paragraphs, please explain what is happening to the current in the circuit to cause the dimming, and why this change in current is happening. 

2. To combat the dimming problem, you decided to rewire the bulbs in Joe’s sign in parallel.  While the bulbs no longer dim as they are added, you notice the battery seems to be draining faster, and faster than before with each bulb you add.  Describe the effect of adding bulbs in parallel to the circuit on the current through each bulb.  Also describe the effect this has on the total current drain in the battery.