<p>Nice, I got all those correct then :)</p>
<p>I remember there was a question that recalled the Pendulum, we had to increase the time period of the pendulum by using the equation T=2pi(under-root)L/g </p>
<p>I don’t remember the choices but what i chose was something related to height, Take the pendulum on top of a building or something like that decreasing its value of g and increasing T. </p>
<p>Does anyone know if its right?</p>
<p>During the test I wrote the new period is greater than T.</p>
<p>I reasoned that if the elevator was accelerating upward, then that can be interpreted as decreasing the gravity. By plugging back into the formula, we have a greater value.</p>
<p>But, uh…, did it say it was accelerating upward or was it just moving up at a constant rate? If it just said constant rate, then I believe the answer is that the period is equal to T. I hope it said that the elevator was accelerating…</p>
<p>I think it said it was accelerating upwards but I’m not sure. What does 4 omitted and about 10-12 wrong look as a score? Is that still a 750?</p>
<p>If you have 1kg of bricks and 1kg of feathers, and kg is a unit of mass and weight is mass multiplied by gravity then 1kg of bricks times 9.8 = 9.8N and 1kg of feathers equals 9.8N, so both mass and weight would be equivalent. right?</p>
<p>Chessspawn: Yes, they will be. But I am saying that “Mass” was not in the options (as far as I remember), Weight was in the options.</p>
<p>"But, uh…, did it say it was accelerating upward or was it just moving up at a constant rate? If it just said constant rate, then I believe the answer is that the period is equal to T. I hope it said that the elevator was accelerating… "</p>
<p>It said accelerating upwards. :)</p>
<p>For the pendulum question:</p>
<p>When you’re accelerating upwards, you’re actually increasing gravity. It seems weird, but if you think of a scale, it just weighs the force you exert on it. If the scale is accelerated against your feet, it will show that you apparently “weigh” more. So the upward acceleration increases the value of gravity, and makes the overall period shorter.</p>
<p>After taking the test guys, any areas you recommend studying a lot? And any review books to get?</p>
<p>I never really studied Waves, so if I were to take the test again, I will do that first. Everything else was pretty much easy.</p>
<p>About the pendulum in the elevator;</p>
<p>Isn’t only the normal force increased? That’s why you’re accelerating upwards. The force of earth remains the same, but the net force is caused because the normal force increases. Scales measure normal force, so that’s why they say you weigh more.</p>
<p>But the force of earth, and g, are the same. Thus, the pendulum’s period would be unaffected.</p>
<p>Am I wrong here?</p>
<p>For any body accelarating upwards in an elavator…F= M(g+a)
For any body accrating downwards in an elavator…F=M(g-a) Source, My physics high school book.</p>
<p>crabsmack:</p>
<p>This is actually a deep idea that you hit on here. 2400StudentNOT’s explanation was correct. Within the frame of reference of the elevator, the pendulum does experience an extra force downwards as if gravity were increased.</p>
<p>Look up the “equivalence principle.”</p>
<p>[Equivalence</a> principle - Wikipedia, the free encyclopedia](<a href=“http://en.wikipedia.org/wiki/Equivalence_principle]Equivalence”>Equivalence principle - Wikipedia)</p>