Physics H131: Hints for Problem Set #10

Chapter N1 Problems

• N1S.6: Draw a free-body diagram for each situation. When the boat is moving, in which contributions can you decompose the contact force between the boat and the water? What causes the boat to be partially lifted out of the water when moving?
• N1R.1: Draw a picture of (a) the sun and Venus orbiting the earth and (b) the earth and Venus orbiting the sun at different radii. Explore how in each case Venus will look to an observer on the earth when passing through various stages of its orbit.

Chapter N2 Problems

• N2S.3: First compute the acceleration vector, then its magnitude.
• N2R.1: You should approach this by considering two extreme cases: moving straight towards the wall, braking as hard as possible without blocking the wheels, and turning left on a circle without braking at all. Given a certain maximum value for the magnitude of the static friction force between the tires and the road, what is the shortest distance until you come to rest in the first case, and what is the smallest radius that you can go on in the second case? Draw a picture of the two situations and draw your conclusions, using reasonable interpolation to estimate the outcome of intermediate situations (some braking plus some turning).
• N2A.1: The "curly d's" in that problem indicate partial derivatives of a function of several variables (here x,y,z) with respect to one of these variables while keeping the other variables fixed. Review Chapter C11 for the connection between potential V(r) and force if necessary.