https://padlet.com/brucekloot1/wasalos6njmq Let's talk exam! en-us 2019-04-12 14:03:34 UTC 2026-01-09 20:50:28 UTC hello@padlet.com https://padlet.com/brucekloot1/wasalos6njmq/wish/352770188 Is this FBD correct ? If so is the angle theta not needed?]]> 2019-04-19 16:00:45 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/352770188 brucekloot1 https://padlet.com/brucekloot1/wasalos6njmq/wish/352781823 FBD nearly correct but use Table D/4 to locate G (semicylindrical shell).
You do need theta.
APOLOGIES, theta was not initially included in the tutorial question but theta = 45 deg has now been added.]]> 2019-04-19 17:19:13 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/352781823 https://padlet.com/brucekloot1/wasalos6njmq/wish/355545190 what value of r was used in this solution to find alpha? I keep getting the wrong answer no matter what value of r I sub into this exact equation. ]]> 2019-04-30 17:26:00 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/355545190 brucekloot1 https://padlet.com/brucekloot1/wasalos6njmq/wish/355646122 Since r = 1m, leaving it out of that exact equation will give you the correct answer!]]> 2019-04-30 22:29:29 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/355646122 https://padlet.com/brucekloot1/wasalos6njmq/wish/355759227 why is the Ia term not included in taking the sum of the moments about A? We just worked out alpha to be non-zero and now are trying to find the force at B at this non-zero value of alpha. ]]> 2019-05-01 12:48:53 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/355759227 brucekloot1 https://padlet.com/brucekloot1/wasalos6njmq/wish/355773888 The alpha that was worked out is the alpha of the links. The platform stays horizontal so Ia is zero]]> 2019-05-01 13:25:35 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/355773888 https://padlet.com/brucekloot1/wasalos6njmq/wish/366307850 In the memo we take the sum of the moments about the centre of gravity of the rod, G, but why would it be wrong to take the sum of the moments about O, the center of the loop, because surely the rod and loop will both have the same alpha value and that way we can avoid even calculating N?]]> 2019-06-07 08:57:55 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/366307850 https://padlet.com/brucekloot1/wasalos6njmq/wish/366327049 Why are we allowed to make the positive directions different for A and B? Doesn't that affect the final answer]]> 2019-06-07 11:00:51 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/366327049 brucekloot1 https://padlet.com/brucekloot1/wasalos6njmq/wish/366334095 Nope, the positive direction does not matter. As long as these are different rigid bodies and we are using the force or momentum equation on them, you can choose any direction you like. ]]> 2019-06-07 11:49:23 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/366334095 brucekloot1 https://padlet.com/brucekloot1/wasalos6njmq/wish/366335035 The problem with taking the moments about O, the centre of the loop (or hoop), is that you need to then use the form of the equation sum Mp = Ia + magd. So it cancels out N but introduces another term which is possible to work out since you need the vertical component of aG - which is aG/O - and then d = r/2. You can do it this way.]]> 2019-06-07 11:56:07 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/366335035 https://padlet.com/brucekloot1/wasalos6njmq/wish/366659104 In lecture 27, particles angular impulse and momentum, in example 2 we include the bullet in the angular momentum equation, even though at first it is moving with a linear velocity only. In tut 12, question 3, we don't include the carriage in the angular momentum equation, even though it is a part of the system. Is this difference because with the bullet, after impact it will also have an angular velocity so we include it but in tut 12 Q3 the carriage never has an angular velocity so even though it is a part of the system we don't include it in the angular momentum eqn?]]> 2019-06-10 08:48:12 UTC https://padlet.com/brucekloot1/wasalos6njmq/wish/366659104