Note this has a piece on relative velocities, too, part of Lecture 5 but not assigned until Homework 1B.

6. one point, from Lectures 5, 6, involves calculation, sketches

(a) .4 from Lecture 5, Translation Rules for Relative Motion. If a ball is thrown with speed 14m/s relative to the passer, and the receiver is running away from the passer with speed 8m/s, how fast will the ball hit the receiver's hands? (.1)
If the receiver is running toward the passer with speed 6m/s, how fast will the ball thrown with speed 14m/s hit the receiver's hands? (.1)
Which of these is a hard and which a soft catch? (.1)
Sketches help here, so do a simple one for each case, and on your sketches label the various speeds clearly with subscripts. Then be sure you also write the relevant equations and label the various speeds clearly as you show your work. (.1) Box your answers.

(b) .6 from Lecture 6, Analysing a Collision. Use Conservation of Momentum to solve this problem: A bike plus rider of mass 75 kg with speed 20 m/s runs headon into a small car plus driver of mass 600 kg with speed 16 m/s. The bike sticks to the car and the whole system proceeds in the direction the car was going. How fast is the accident traveling? (.1)
Sketch this one, too, before and after, with all the quantities and directions labeled (.1). Write the general conservation equation (.1), then the specific equation for this case (.1), and show your work (.2). Box your answer.

7. one point, from Lecture 7, a group question, involves some equations, mostly words

(a) .6 Newton's Laws of Motion. State Newton's three laws in words and equations (if appropriate), and say what each contributes to our understanding of the concept of force without just repeating what the law is. ("Characterize" the three laws.)

(b) .4 Interpreting Newton's 3 Laws. Mechanics is the branch of physics which includes kinematics plus dynamics. What distinguishes dynamics from kinematics? (.1)
What is meant by initial conditions? (.1)
How does the second law imply determinism? Include in your answer what determinism means. (.1)
In a collision, momentum is conserved. How is that statement equivalent to the third law? (.1)

8. one point, from Lecture 8, involves words and minor calculation,

(a) .4 The force law for gravity. How is an object's weight related to the force of gravity on the object? (.1)
Why does the force of gravity depend on both masses? (.1)
Why does the force of gravity depend on the inverse square of the distance between masses, instead of the distance or inverse distance, for example? The answer is a plausibility argument. Use a sketch if you wish. (.1)
Why is the constant G needed in the force formula? (.1)

(b) .4 A strange and Universal Law. What is the meaning of "universal" in Newton's Universal Law of Gravity? (.1)
How can the weakest force in nature hold the whole universe together? (.1)
Why do we say the mass in Newton's 2nd Law is "inertial" mass and in Newton's Law of Gravitation is "gravitational" mass, when they are the same mass? (.1)

(c) .3 Understanding 1/r² forces. What happens to the force of gravity F between two objects when their separation distance r-->5r? (.1) r-->r/5? (.1)
Given the force F between two masses m1 and m2, what is the force (as a multiple or fraction of F) between 2m1 and 3m2? (.1)
Show that work, box those answers!

9. one point, from Lecture 9, involves calculation and doing an actual experiment

(a) .4 Work and Potential. What is the difference between an elastic and an inelastic collision? (.1)
What is negative work? (.1)
What is the meaning of the word ``potential'' in potential energy? (.1)
What did the bowling ball in my face demonstrate? (.1)

(b) .3 Conservation of Energy. A high jumper runs at v=6m/s, makes a perfectly efficient jump, and sails to what height? (It would be his/her center of mass that would rise that far.) You must use conservation of energy to solve the problem, even if there's another way. Use g=10m/s². Show your work! You may be surprised that the answer doesn't depend on the jumper's size in this idealized world of physics laws about simple, ``perfect'' systems. (.3)

(c) .3 How Powerful are You? Students in physics courses with labs are required to run up the Sterling Hall stairs as part of one of their labs. I'd like you to do something similar, but it's OK if it's fairly crude. If you are physically unable to do this, call me or write me a note AT ONCE, and I'll give you an alternate problem.
Do this with a partner if possible. Pick some stairs, for example two or three flights in Sterling Hall, or in a dorm. It should be a significant number, longer than one average flight. Take a ruler and a stopwatch or at least a watch with seconds displayed. Measure the total height you will be raising your body, convert it to meters (1m=39.37in, or 1in=2.54cm), then run up the stairs as fast as you can, timing yourself. It won't be very accurate, but calculate your power output. You'll need your mass, using 1kg=2.2lbs, so divide your weight in lb by 2.2 to get the number for your mass in kg. Use g=10m/s². Show your work! (.3)

10. one point, from Lecture 10, some covered in Lecture 6, a group question, involves words

(a) .2 Why doesn't it fall down? What are two differences between the force of gravity and the force of electricity? (.2)

(b) .4 Causality. Give two properties of a causal relationship. (.2)
How does Newton's concept of action at a distance violate causality? (.1)
How does Faraday's concept of field guarantee causality? (.1)

(c) .4 Fields. What is the difference between the field lines in general in electricity and magnetism? (.2)
What is the relation between a force and a field? (.1)
How can something (a field) be real but intangible? (.1)

11. one point, from Lecture 11 and all of Unit 1, involves words and a picture

(a) .2 from Lecture 11, The Nature of Light. How did Maxwell know that light is an electromagnetic wave? (.1)
What combination of electromagnetic constants gives the value of the speed of light? (.1) Be sure you learn that value!

(b) .5 from Lecture 11, Making the Equations more Symmetrical. What is a magnetic monopole? (.1) May it exist? (.1) What does it have to do with the difference between electric and magnetic field lines? (.1)
Describe displacement current in terms of a capacitor. (.1) What two symmetries does the displacement current guarantee? (.2)

(c) .2 from all of Unit 1, Shoulders of Giants. Maxwell illustrates Newton's famous, though probably plagiarized, quote, ``If I have seen further than others, it has been by standing on the shoulders of giants.'' How did his physics depend on the physics of at least two of his predecessors? (.2)

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