these questions are challange questions from our teacher (MIT grad) who gave us these knowing that they were a bit out of reach for us as we are a beginning intro physics class(HS). we haven't but scratched the surface on these topics. so we're trying to find/acquire at least a basic, rough understanding so we can say "ah ha. you've not been completely successful in stumping us." because he gets a laugh when we come in and don't have a clue. and he wins. so our whole class is desperately looking for something to show for these problems. here are some physics questions that i am puzzled on and lost. help! if you are able to solve them please show how, or at least what formulas/equations you used to get there. thanks! (even if you have a clue take a shot!anything could help). 3.gold has a density of 1.74x10^3 kg/m^3. calculate the gravitational field strength 10m from a 1m cube of gold. 4.the 3.56g bullet from a 22-250 rifle is fired vertically into a 1.174kg block of wood. the bullet sticks to the block, which rises 0.595m. what was the speed of the bullet at impact? 6.if an astronaut dropped a small rock on the surface of mars, how far would it fall in 1.00 seconds? the mass of mars is 0.107 that of earth and the radius of mars is 0.53 that of earth. 8.calculate the mass of jupiter from the information that its moon Io orbits at an average distance of 4.22x10^5km from jupiter's center and has an orbital period of 42.5 hours. 10.a spacecraft travelling at 0.8c away from the earth launches a probe that is travelling 0.95c from the spacecraft's frame of reference. what is the speed of the probe from the point of view of the earth? 11.what is the acceleration due to gravity 1000km above the surface of the earth? for #11 i used the formula : acceleration = change in speed/ time interval and got what seems to be a logical answer....(this was the right equation ..right?) for #10 i multiplied 0.8 times 3x10^3 (the constant for speed of light) and 0.95 times the same : 3x10^3. was this a right move? what should i do with these values now? it doesn't give me distance or time values. so what eqaution can i plug these values into if they are all i have? 4 seems like it didn't give me enough values.