Will this work with yosemite

If you are talking about using this: Installing MacBook Pro 15" Unibody Mid 2009 Dual Hard Drive to then install either a HD, SSHD hybrid or SSD drive you're all set from the hardware side! I do recommend going with a SSHD like the Seagate Laptop SSHD or a Samsung 850 EVO 120 or 250MB SSD. Just remember this is an older system so its lifespan is limited. Be careful you don't put to much into it.

Here is the Apple Yosemite Upgrade page: Upgrade to Yosemite. Basically, If your Mac can run OS-X Mavericks, it can run OS-X Yosemite.

But before you upgrade the hardware or the OS I would recommend you make sure your systems firmware is up to date. Follow this Apple T/N: About EFI and SMC firmware updates for Intel-based Mac computers. You may also want to get from IFIXIT the Universal Drive Adapter so you can prep up the drive externally before you install it.

You may want to consider just replacing your current HD as a cheaper option using the universal adapter you can migrate your stuff to the new drive. Here's the IFIXIT guide to replace your current drive: MacBook Pro 15" Unibody Mid 2009 Hard Drive Replacement