<p>nothign can be faster than c, i believe.</p>
<p>I thought I already addressed the spaceship problem? As Dina said, nothing can be faster than c....</p>
<p>And anyhow, the formula for the addition of relativistic velocities is: v=(v1+v2)/(1+(v1*v2)/c^2)</p>
<p>This is the formula to use because you have the ship going at 0.7c... The ship sees the probe pass by at 0.6c, which means that to find the speed, you need to add the two velocities. However, when you have velocities in terms of the speed of light, you need to use the formula above rather than just v=v1+v2.</p>
<p>By plugging in the numbers, you get:
v = (.7c + .6c) / (1 + (.7c*.6c) / c^2)
= 1.3c / (1 + 0.42c^2 / c^2)
= 1.3c / 1.42
= 0.915...</p>
<p>Yeah?</p>
<p>I skipped the spaceship question.</p>
<p>I thought it was kinda hard...</p>
<p>that question was definitely 1/9</p>
<p>F=G(Mm)/r^2=ma, where a is the acceleration</p>
<p>so a=GM/r^2</p>
<p>thus, a is inversely proportional to r^2 (otherwise known as the "inverse square law")</p>
<p>pay attention to the diagram, the 3R refers to the distance between the satellite to the centre of the earth, not that to the surface of the earth. If it were the surface of the earth, distance would be 4R and the answer would become 1/16</p>
<p>re: spaceship problem</p>
<p>nothing can be faster than c, and only light could be at c</p>
<p>rs8389is right...</p>
<p>for the wet-road problem, i was vacillating between reflection and refraction. however, it came to me that refraction at the surface of water only accounted for a minor influence. when the road is dry, light bounces off the road at various angles so some of the light rays re-enter driver's eyes, but when the there's water on the road light reflects forward and it's really hard for drivers to capture the reflected light</p>
<p>does anyone know the scoring guide for Physics in the blue collegeboard book? Also, for the question that was asking if something was spinning in a circle, what would happen if the string were cut, the answer is it would move in a stright line, perpendicular to the string, and away from the object that it was attached to? And does sound wave refract when it enters a new medium? (the question about what the similarities are between light and sound waves) There was also another question about light and sound waves, which I can't remember, and I put E. Does anyone remember what the question is?</p>
<p>Sound waves reflect, refract and diffract. They do everything that light waves do. I got those two questions wrong. 555...</p>
<p>yeah, I want to find out about the two wires I and 2I and point P between them and waht is the distance to the 2I wire?</p>
<p>another question is the .. two ends of a bar magnet are put near iron filings in turn. Do they both attract the iron filings? attracts and then repels? or else?</p>
<p>Finally, ANYBODY REMEMBER THE LAST QUESTION?</p>
<p>that's wrong ray
you cancelled out the two c^2 in the denominator without taking into account the 1.
therefore it should be
v = (.7c + .6c) / (1 + (.7c*.6c) / c^2)
= 1.3c / (1 + 0.42c^2 / c^2)
= 1.3c / (1/c^2 + 0.42)
= 928571421.2...</p>
<p>Lol, Colin, look at the equation again. The denominator is (1 + (v1 * v2)/c^2)... By order of operations, the c^2 only divides (v1 * v2). I still stick with my original answer....</p>
<p>sounds do everything except polarization..</p>
<p>in reference to the bar magnet/fillings question.. i think both sides attract because in class we did an experiment and the fillings were attracted to both sides and organized themselves in field line patterns</p>
<p>2 attract 's .</p>
<p>yeah, I put 2 attract</p>
<p>i'm kinda desperate to know the official score conversion for Physics (not the one from PR, the one in the official blue book) Thanks</p>
<p>well, skipping 16 is an 800</p>
<p>for those who used PR or sparknotes for the exam, how well did it prepare you?</p>
<p>well, PR is fine, but still covers stuff you don't need to know for the test, and lacks stuff you need to kkonw fort the test.( waves, sound, polirization,etc) sparknotes is fine...i would suggest use PR along with Sparknotes......if you want to use these 2 books.</p>
<p>thanks Dina :D!</p>
<p>what about a raw score of 55 what would that translate to...</p>
<p>55=770, according to the CB guide.</p>
<p>guys, I just realized we are doing "illegal" things a lot of the time in these subject test posts, by sharing and discussing the test problems....which according to collegeboard. might lead to some "serious results"....I personally really do not like that rule, I'm just reminding in case someone want to stop doing that....</p>