Physics 1090: Fundamentals of the Physical Universe

Unit 2: Force and Motion
Due September 7, 2011
20 points

Part 1: 15 points

Answer one, and only one, of the questions in Part 1.

These questions are for you to combine different ideas from the unit and apply them to situations not directly addressed in class or in the textbook.  Think about the situation, and about the physics that applies to it.  See me for help if you are stuck.

1. Motion graphs.

Draw and explain the position-time, velocity-time, and acceleration-time graphs that correspond to at least three of the following processes.

• A basketball bounces up and down, each bounce lower than the one before it.
• A car steadily accelerates from a stop to its cruising speed, which it maintains for a while.
• A yo-yo unrolls down and then rolls up its string.
• A baseball player stands at first base, sprints, and slides into second base.
• A coconut falls from a tree and lands on the sand.
• A child swings back-and-forth on a swing set. (Analyze the motion in the horizontal back-and-forth direction, not in the vertical up-and-down direction.)
2. Justify Newton’s first law.

Newton’s first law is not intuitive.  State Newton’s first law in your own words.  Then explain why, in normal experience, it does not appear to be true (even though it really is true).  What must be happening? Give concrete examples to support your argument.  Your answer should be several paragraphs long.

3. Explain Newton’s second law.

Express Newton’s second law in words.  Explain what each of the quantities in the law means, and how they are related.  Which quantities are causes and which are effects?  Give a concrete example of how the law applies in a specific situation.

4. Concept map.

Draw a concept map incorporating the ideas of position, time, velocity, speed, acceleration, and force.  Other concepts that would be appropriate include (but are not limited to) change, positive, negative, and direction.

5. Analyze the unit.

Summarize the key scientific point that each of this unit’s activities was intended to teach.

• Ball on a tray
• Stickball
• Motion graphs (real-time graphing of position, velocity, and acceleration)
• Rail carts
• Balls on ramps

Take your choice of these tasks.  Do not submit answers to more than one of them. Just choose one, and submit it.  Your answer should thoroughly address all points of the question.  An adequate answer will be several paragraphs long.

Part 2: 5 points

• Reflect on your experience.

Think back to when you actually did the activities in this week’s unit.  What were your feelings during the activities?  (Were you physically tired? Bored? Excited? Distracted? Confused? etc.)  You don’t need to explain the reasons for your feelings if you don’t want to.  There will be no penalty for saying you dislike the class.  The purpose of this question is for you to be mindful of your own circumstances.

Warning: Do not turn in paper that has ragged edges!  If you write your work in a spiral-bound notebook, trim the edge before submitting it.  Papers with ragged edges will be returned unmarked.