<p>Photo emission was bohrs model.
There was one in which you had to find the seconds required to raise tmperature of a water.
Heat energy = 500g x 4.2j/g x 20 = 42000
then u had to divide 42000/(power of heater) whatever. I dont remeber the rest but the answer was definitely 100 seconds.</p>
<p>then there was also this question about some engine absorbing Q1 amount of heat then doing work W and then releasing the remaining heat Q2 in exhaust gases. I chose Q1 = W +Q2 option. anyone remember this.</p>
<p>ya i chose the same option. First I was considering Q1>W+Q2 but then changed to first one. Which one is right?</p>
<p>there were also question about perpetual motion. the answer of the question " how do you sustain perpetual motion" was like eliminating all energy losses. Another part was at whchi part will the ball has the maximum force. I chose the space inside the cylinder where it was just released as acceleration was the greates there and therefore force would also be the greatest. Then there was another question about 2 charges in a electric field pipe. What was the amount of work done. i chose same. but i chose that electron would have greater acceleration because it is lighter. Another question was about a hot air ballon exerting an upward force of 840N. it lifts a wieght of 75 kg. What is the approximate acceleration. i chose 2.
F= ma
840-750 = 75 a
140 = 75 a
a is approximately 2.
then there was also some question about a man wearing a spacesuit wieghing the same on moon as on earth without spacesuit. his mass is 75kg. The g on moon was 1/6 the g of earth. u had to find the (mass or wieght ????) of the spacesuit.
Wieght on earth = wieght of man on moon + wieght of suit on moon
75g = (75x(g/6)) + M(g/6)
75g = (g/6)(M+75)
75 = (M + 75)/6
75x6= M + 75
M = 375</p>
<p>I got the same answer except acceleration - I put electron and proton had the same - stupid me - didnt think of mass :</p>
<p>I think the first one is right because Q1 is the main energy. W and Q2 are part of Q1.</p>
<p>yea but I wasnt sure if there is some additional energy</p>
<p>slipups happen. i messed up the star question insted of red shift i chose voilet shift</p>
<p>but i heard the curve is a lot lenient on physics. Lets just keep our fingers crossed.</p>
<p>perpetual motion questions .... why was it energy... how about elimination air resistane?</p>
<p>well fortunately I have changed it to = sign :)
Yea I hope the curve will be high enough :)
isnt a resistance causing a loss in energy?</p>
<p>there was a question about image of a tree - what did you put?</p>
<p>well there was 2 different choices .... eliminating all the energy or something ... and the other one was eliminating air resistance ... what was it?</p>
<p>the first choice was a distractor. the last choice (correct one) was " Somehow Finish all the energy losses". In perpetual motion you have to mantain the same energy level. Energy can be lost by air resisteance but also by the heat genrated in the springs. enrgy can also be lost as sound energy when the ball hits the spring. so you have to eliminate all energy losses to attain perpetual motion ( this is the motion which can go on forever on its initail energy)</p>
<p>In the image of tree i guess this is the projector question. the image would be real and inverted.</p>
<p>by the way what is a distractor? And there was a problem about Hubble telescope - I had no idea about it - do you remember?</p>
<p>oh kewl I think I got it right - I wasnt sure if it would be smaller :)</p>
<p>FOr how long it takes to boil water 20 degrees - 100s. Use q=mct to find out how much it changes in one second, then you can figure out how many these second increments you need for your 20 degrees.</p>
<p>a choice that looks like the right choice but actually is a trap. The hubble constant question was that what does the hubble constant do. i selected "it helps make infrerences about the age of the universe." it was a guess. But it turned out right. Heres the stuff i found on the net on hubble </p>
<p>Hubble Law: the larger the distance () of a galaxy the larger the Doppler red shift of its spectrum the larger the recession velocity ()
- mathematically: , Hubble Constant
- ie. if Galaxy A is twice as distant as Galaxy B Galaxy A is receding from us twice as fast as Galaxy B
- the Hubble Constant () has units of velocity/distance: (kilometers/second)/Mega-parsecs (km/s/Mpc)
- Significance of Hubble Law: the Universe is expanding!
- Important for Cosmology: If we know the value of the Hubble Constant, can calculate size & age of Universe</p>
<p>"by the way what is a distractor? And there was a problem about Hubble telescope - I had no idea about it - do you remember?"</p>
<p>Distractor = choice designed to look plausible and thus lure you away form the correct answer.</p>
<p>Hubble - the problem asked about the constant, not telescope. Hubble law (which uses the constant) relates velocity of a remote system with its distance.</p>