<p>Wait, why should the tension be added up?
I have put in 1W, because the tension should be the same along the string, if the tension is 2W than both the weights will have an acceleration upwards.</p>
<p>the test was enough for me to get a perfect 800 !</p>
<p>It was just W because there was no acceleration so the tension force equals the force of gravity which is W.</p>
<p>It asked for the tension in the cord connecting the pulley and the celiling and not the pulley and the block. So it’s W + W = 2W</p>
<p>Yeah but the tension force is the same for both blocks, so the tension on block 1 is the same as the tension on block 2. You wouldn’t add tension because the rope simply redirects the tension force.</p>
<p>for the bell question, was the greatest acceleration 1 M down since going up goes against the force of gravity?</p>
<p>^velocity*</p>
<p>Hahaha, I got the bell question wrong. I stupidly put that it had the same speed everywhere. zMatrix, I think the correct answer should have been 1 m going down due to the very reasons you’ve mentioned. </p>
<p>What would a raw score of 57 be on this test? A 780/790?</p>
<p>[Pulley</a> - Wikipedia, the free encyclopedia](<a href=“http://en.wikipedia.org/wiki/Pulley]Pulley”>Pulley - Wikipedia)</p>
<p>The net force on the pulley axle should be zero because it is in equilibrium. Since the 2 weights exert a net downward force of 2W the tension in rope joining pulley to roof should be 2W.</p>
<p>@karan11295 - Shouldn’t the net force on pulley be 2W since it supports the weight of 2W at equilibrium? And for the tension I think it should be 1W because the tension is the same along the rope and if the tension=2W each of the weight will undergo an upward force of 2W and acceleration of 1W/m.</p>
<p>Let me say it again. The pulley has no acceleration. So the net force on the pulley is zero. It is supporting a weight of 2W which is acting downwards. So the tension in rope connecting the pulley to roof needs to be 2W upwards for it to balance the weight.
Also the tension in the ropes connecting the weights to the pulley does NOT act on the pulley. It acts on the weights ONLY and balances them. Its value is 1W in the both the ropes and keeps the weights in equilibrium.
You are trying to calculate the tension in the rope connecting the weights to the pulley. We need to calculate tension in the rope connecting the pulley to the roof.</p>
<p>did you guys think that there is no area on the theater wall or something where there is no light for the Red Green Blue light problem?</p>
<p>conservation of energy would say 1m up and 1m down have the same speed but because once it hit the bell some of its energy got converted to sound the bell question should be 1 m going UP</p>
<p>Did the pulley question ask the tension between the rope and the ceiling?!
damn it…</p>
<p>Also, I can’t seem to remember these questions…?
-change in kinetic energy = 0
-increase in velocity when the ball is placed higher
-bulb is always on
does anyone recall them?</p>
<p>For the bell problem, I chose 1m down. Correct me if I am wrong (and if I am, don’t be too hard on me, I am just proposing a solution), but we know that the initial velocity is highest when near zero (ground), so it would make perfect sense that when it is 1 meter away, most of the velocity would still remain (because the downward acceleration due to gravity is reducing most of the speed). However, once it hits the top, we don’t know how much velocity it lost (as far as I am concerned). Then, according to Newton’s third law, the thing will come down with some of the previous force (the other being lost in the bell) plus the gravitational acceleration (this time both of the accelerations are going downward [same direction], allowing for the velocity to increase) This velocity could even be higher than when it was going up, but I couldn’t tell for sure so I had to let my instinct decide. Maybe (n order to compare) this problem could be solved by obtaining a random number and plugging it in (I didn’t try that for I did not want to lose time). I also feel that there was a lack of necessary information that could allow for a better contrast among the point locations. Again, this is how I saw it, maybe I am wrong, so please tell me what you guys think (it will help us all gain a better understanding for the future).</p>
<p>@Grinver: Although instinct says the velocity should be more 1m downwards,it actually will be more when it is 1m upwards.
Suppose when we hit it,it gets an energy E. Due to the energy it starts moving upwards. At 1m upwards E=mg(1)+0.5mv^2 (PE+KE v=velocity)
When it hits the bell,some energy is lost as sound. Now total energy becomes E’ (E’<e). when="" it="" reaches="" the="" point="" 1m="" downwards="" e’=“mg(1)+0.5m(v’)^2” (pe="" is="" same,new="" velocity="" v’)="" since="" e="">E’ v>v’
So velocity is more going upwards.</e).></p>
<p>PS-I got it wrong on the test too. Didn’t pay much attention. :D</p>
<p>@william 22 </p>
<p>change in kinetic energy was the answer to the question where a charged particle was revolving in a circular fashion in constant magnetic field.</p>
<p>the ball’s velocity was higher when it was placed higher ( the ball was sliding from a ramp)</p>
<p>Dont remember the bulb question</p>
<p>What did you guys mark for the room question with area, thickness and the temperature of the room?</p>
<p>There was actually atleast a color (blue, green or red) falling in each regions for that cardboard question.</p>
<p>we had to find the tension in string not net force so the answer is w both of u r rong</p>