Original post by isiaiah d
if a question says find the answer in terms of ... do I need to include all of the variables mentioned?
yes
post the question so we can be completely sure?
Original post by BobbJo
yes
post the question so we can be completely sure?
post the question so we can be completely sure?
http://i-want-to-study-engineering.org/q/rod_on_springs/
I think you can take moments about the end of the rod that will give an equation that includes all the variables but they don't have alpha in their answer
Original post by isiaiah d
http://i-want-to-study-engineering.org/q/rod_on_springs/
I think you can take moments about the end of the rod that will give an equation that includes all the variables but they don't have alpha in their answer
I think you can take moments about the end of the rod that will give an equation that includes all the variables but they don't have alpha in their answer
Take moments about the midpoint
T1 x 3 alpha = T2 x 4 alpha [T1 and T2 are the tensions in the springs]
so alpha cancels in the moment equation
[p.s usually questions like this will involve all variables, but not always as this one didn't]
(edited 5 years ago)
Original post by BobbJo
Take moments about the midpoint
T1 x 3 alpha = T2 x 4 alpha [T1 and T2 are the tensions in the springs]
so alpha cancels in the moment equation
T1 x 3 alpha = T2 x 4 alpha [T1 and T2 are the tensions in the springs]
so alpha cancels in the moment equation
so we don't need alpha in the answer? If we take moments about the end you can still cancel K_2 and have an answer in the terms they included but it would have alpha and the way they did it the answer doesn't have alpha but it's simpler, is there any advantage to either way?
Original post by isiaiah d
so we don't need alpha in the answer? If we take moments about the end you can still cancel K_2 and have an answer in the terms they included but it would have alpha and the way they did it the answer doesn't have alpha but it's simpler, is there any advantage to either way?
no we don't need alpha in the answer as it turns out alpha cancels out
if you take moments about the end, do you get the correct answer? (4th answer) it should be possible anyway you do it provided all forces and directions are correct
the advantage about taking moments about the midpoint is that the distances are simpler and one force (weight) has no moment
Original post by BobbJo
no we don't need alpha in the answer as it turns out alpha cancels out
if you take moments about the end, do you get the correct answer? (4th answer) it should be possible anyway you do it provided all forces and directions are correct
the advantage about taking moments about the midpoint is that the distances are simpler and one force (weight) has no moment
if you take moments about the end, do you get the correct answer? (4th answer) it should be possible anyway you do it provided all forces and directions are correct
the advantage about taking moments about the midpoint is that the distances are simpler and one force (weight) has no moment
ok, it's just confusing because I took moments about the midpoint to start and thought it was wrong because alpha was eliminated.
I took moments from the end and couldn't really simplify it down to the fourth answer but I don't think I made any mistakes.
thanks!
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