Question

Hi everyone! Can someone please confirm an algebra mistake for me? I attached a picture of the work. Shouldn't it be "m" on the bottom and not "2m"? Thanks!

Answer 1

It was \(\dfrac12M+m\) now it's \(\dfrac12(M+2m)\)

Answer 2

are you asking me or telling me?

Answer 3

I'm telling you that it's correct

Answer 4

can you please show me how they got 2m on the bottom? can't figure it out

Answer 5

wait...are you telling me the 2m is correct or m is correct?

Answer 6

\[\left[\frac12MR^2+mR^2\right]\omega=mv_id\]\[\frac12\left[MR^2+2mR^2\right]\omega=mv_id\]\[\omega=\frac{mv_id}{\frac12(MR^2+2mR^2)}=\frac{2mv_id}{MR^2+2mR^2}=\frac{2mv_id}{(M+2m)R^2}\]

Answer 7

haha...yikes! thanks a bunch! I see it now! :o)

Answer 8

no problem :)

Answer 9

one question...

Answer 10

if you factor out a fraction from a coefficient of 1, it's like 1 divided by (1/2) which equals 2 right?

Answer 11

yep

Answer 12

wow...you don't see that everyday...it can sneak up on you! thanks again!

Answer 13

no problem

Answer 14

another way to see it
\[ \frac{MR^2}{2} + mR^2 \]
put the 2nd term over a common denominator, by multiplying by 2/2
\[ \frac{MR^2}{2} + \frac{2mR^2}{2} \\
\frac{MR^2+2mR^2}{2}
\]

Answer 15

thanks phi!