1. The problem statement, all variables and given/known data A proton sits at coordinates (x; y) = (0; 0), and an electron at (d; h), where d >> h. At time t = 0, a uniform electric field E of unknown magnitude but pointing in the positive y direction is turned on. Assuming that d is large enough that the proton-electron interaction is negligible, the y coordinates of the two particles will be equal (at equal time) (a) at about y = d=2000; (b) at an undetermined value since E is unknown; (c) at about y = d=43; (d) nowhere: they move in opposite directions. 2. Relevant equations qE=F=ma 3. The attempt at a solution I chose b, but the answer is a Q2 Question 20 TheWebb space telescope, scheduled to be launched in 2010, will have a mirror 6m in diameter. Compared with the Hubble space telescope, whose mirror has a 2:4m diameter, it will be able to resolve objects whose angular separation is about (a) 2.5 times smaller; (b) 5 times smaller; (c) an order of magnitude smaller; (d) the same: the larger mirror only increases the amount of light gathered. (no idea of telescope) Q3 A person pulls a box along the ground at constant speed. Considering the Earth and the box together as a system, which of the following is true about the net force F exerted by the person on this system and the work W she does on it? (a) F = 0 and W = 0 ; (b) F != 0 and W = 0 ; (c) F = 0 and W != 0 ; (d) F != 0 and W != 0 . These are not hw problems, just contest prep. It would be great if someone can give me a sol'n as i have spend some time thinking about the problems already. Thanks!