I just got back from doing my physics exam, didn't do so well, but I did well during the semester and I think I did well on a final summative project. This is gr. 11 by the way, so nothing to fancy. Anyway, I wrote down the questions i wasn't sure of, and I just want someone to help me out with the answers please: 1. 4 students timed(something) and got the times 1.85, 1.8, 1.9, and 2, what was the average? I know this looks really basic and all, the answer I got was 2, simply because of following the significant figure rules: 1.85 + 1.8 + 1.9 + 2 = 7.55, accurate to no dec. place because of the number '2'. Therefore it's 8, divide by 4 = 2, accurate to one sig fig, wierd result yes, but that's how I did it, look alright? 2. Which of the following demonstrates newton's 3rd law? turning a corner 2 skaters pushing against one another and being sent backwards earth held in orbit by the sun friction of driving on a road(I think) car tires slipping I think it's the one with skaters, although in some sense the 3rd law can be seen anywhere, I also thought the earth one was possible, because the sun pulls the earth, and so the earth pulls the sun, I don't know, someone please tell me if I'm right, it wasn't the best question I know but... 3. What is true about the gravitational field strength of earth? 9.8 everywhere greatest at equator smallest at the top of mt. everest largest at the deepest spot in the ocean largest at the poles It's one of the last two I'm pretty sure, though really only the last makes sense, sort of since the earth bulges at the equator, and the radius is smaller at the poles. Though none are really true, because you can go higher than mount everest, and lower than the ocean floor and the poles, but what would you say? 4. Which of the following does not contribute to kinetic friction? mass coefficient of friction normal force applied force gravitaitional field strength I guessing normal force, though I'm not sure; I was absent when we did most friction related stuff, could someone correct and explain why? 5. What's the angle of the reflected ray with an incident ray of 34 degrees? 0 34 56 66 74 I'm thinking 56, because we were told that reflected rays make a 90 degree angle with the incident ray... so 90 - 56 = 34, am I right? 6. What's the critical angle of ethyl alchohol(index of refraction 1.36) in air(index of refraction 1.0003)? Or was it the other way around? 47.3 0.0257 90.0 48.8 45.0 I'm thinking 47.3 sin(critical angle) = n_2/n_1 theta = 1.0003/1.36 sin(inverse) = 47.35 or something like that, am I right? That's all for now, thanks, someone please help soon.