<p>1) two Blocks of equal weight W are suspended over a massless frictionless pulley that is hung from the ceiling. When the blocks are at rest, the tension in the cord supporting the pulley is:
a) zero
b) w/2
c) w
d) 2w
e) 3w
ans:d</p>
<p>2) a person on Earth observes a particle traveling east at a relativistic speed of 0.6c and a spaceship traveling west at 0.^c. Which of the following correctly describes the particle's speed as measured by an observer in the spaceship?
a) greater than c
b) c
c) greater than 0.6c and less than c
d) 0.6c
e) less than 0.6c
ans: c</p>
<p>3) At the boiling point of a liquid in an open beaker, which of the following equations must be true?</p>
<p>a)temp of liquid = temp of surrounding air
b) absolute temp of liquid= 273 degrees C
c) vapor pres of liquid at the surface = atm pressure
d)pressure exerted by liquid at the middle of the beaker walls= pressure exerted by liquid on the beaker
e)2* (vol of liquid)= interior vol of beaker</p>
<p>ans: c</p>
<p>Also, these are some question from review sheets my teachers used to give me</p>
<p>please please PLEASE help!</p>
<p><a href=“Dropbox - Error - Simplify your life”>Dropbox - Error - Simplify your life;
<p>Wait… what’s your question? </p>
<p>Explanations?</p>
<p>I’m really bad at explaining, so hopefully someone else will help. Plus I’m probably crap at Physics by now.</p>
<p>It’s okay I’m sure you’re not THAT bad :P</p>
<p>No one here knows or what?! 
:/</p>
<p>For Q.1 it will b easy to visualize the situation if you draw a free body diagram. As the question mentions that two weights suspend over a pulley (attached to a massless cord), the two weights hang downward, exerting force, equal to their weights, downwards. Thus, the tension on the cord acts upward and its magnitude will be the same as the sum of the two weights, 2w ( Newton’s 3 rd law)</p>
<p>For q.3 All I know is that its just a law. Generally, when vapor pressure( pressure exerted by vapor over the liquid surface) equals atmospheric pressure, the liquid boils. If you aren’t sure what vapor pressure is, this pic can help you to visualize it: <a href=“http://upload.wikimedia.org/wikipedia/commons/6/67/Vapor_pressure.svg[/url]”>http://upload.wikimedia.org/wikipedia/commons/6/67/Vapor_pressure.svg</a> </p>
<p>For q.2 what do you mean by 0.^c.? Please check the question then I’ll b able to answer.</p>
<p>For questions from Drop box files:</p>
<p>Q.41 The Q. already states that the plates have a uniform elec. field in between. So, the answer is obviously E.
Mathematically,
F=EQ … E is uniform and same +ve point charge is used, so Q is also the same for every point …</p>
<p>Q. 71
(I) incorrect as both sun n earth experience equal force
II correct. As both experience equal force but sun has greater mass so its acceleration is less. ( apply F= ma)
III correct. Kepler law states that.</p>
<p>Ans. E</p>
<p>Q. 72. I’m pretty sure the answer is E coz momentum is conserved everywhere in nature.
(I) it describes elastic collision so it definitely obeys the law
II it describes inelastic collision n it also obeys
III I’m not sure, but I guess the question describes elastic collision once again.</p>
<p>Q 67
The satellite would crash to earth if it had been stationary(relative to earth). But as it revolves around earth with a const. Orbital vel, the grav. force supplies the necessary centripetal force. So ans is E. </p>
<p>U may choose choice c but it is incorrect as net force on the satellite is not 0, had it been 0 it could never orbit the earth as it would lack the necessary centripetal force. Also there is no force called centrifugal force. It is just a fictious force.
Sorry, if my explanations are not clear. Its 1 am here and I’m feeling quite sleepy 
…</p>
<p>in question 2,
sorry typo. it’s 0.6C</p>
<p>and THANK YOU!</p>
<p>Feels good to be noticed 
</p>
<p>Are you taking sat phys?! </p>
<p>You seemed to solve them so effortlessly, I sorta envied you
But I guess should have figured from ur name ;)</p>
<p>Yes, I am.
For q.2 If u apply classical mechanics, u’d say that the guy in the spaceship would measure the speed of the particle to be 1.2c [ .6c- (-.6c) ] as the particle is moving to the direction opposite to that of the spaceship… (refer to relative velocity chapter if u haven’t understood this calculation) . But 1.6c > c which can’t b true as special relativity restricts it. (So, sp. relativity tells u tht no one can beat me(photon) in a race :P)So the answer is obviously choice C.</p>
<p>“But 1.6c > c which can’t b true as special relativity restricts it. (So, sp. relativity tells u tht no one can beat me(photon) in a race :P)So the answer is obviously choice C.”</p>
<p>I don’t get it at all.</p>
<p>So the speed will be greater than the speed of light, and somehow the answer is “greater than 0.6c but less than c” </p>
<p>how
come
?</p>
<p>According Einstein’s special theory of relativity, nothing can move faster than light or the speed of light is the maximum speed possible to achieve and speed of light is denoted by c. So, any particle other than photon(the particle of light) cannot have speed greater or equal to c, so that’s why the answer is choice C.
And that race thing is just a joke related to this question(As my CC username is photon so I was telling that according to sp. relativity, no other object can move faster than light(or photon) n that proves that nobody can beat me in a race… If u didn’t get the humor then you may just ignore it… 
See:
Speed - Wikipedia<em>of</em>light</p>
<p>‘‘Special relativity predicts a non-linear velocity addition formula which prevents speeds greater than that of light from being observed.’’ –> Introduction - Wikipedia<em>to</em>special_relativity</p>
<p>Lol I got the humour just not the explanation.
Now I get it thwnk you very much xP</p>
<p>Are you taking, in nov btw? Oh God I have a ton of questions! Ramn my school for not offering AP s or honors -_-</p>
<p>Yes, I’m taking sat phy. n mth 2 in Nov. N u?
Also, feel free to ask any questions related to phy or math or any of the sciences. BTW r u a high sch senior?</p>
<p>Yes I am! X.X you?</p>
<p>I’m taking chem and phys.</p>
<p>And THANK YOU FOR THE OFFER.
I will sure make the most out of it ;)</p>
![http://upload.wikimedia.org/wikipedia/commons/6/67/Vapor_pressure.svg[/url]](http://upload.wikimedia.org/wikipedia/commons/6/67/Vapor_pressure.svg%5B/url%5D){kind=link}
![http://images.tutorvista.com/content/electricity/dc-generator.jpeg[/url]](http://images.tutorvista.com/content/electricity/dc-generator.jpeg%5B/url%5D){kind=link}
