Can you collect unemployment if you failed your-spacespace-physical and lose your job?

The best answer we can give is "maybe".

Rules vary from state to state, but the California eligibility requirements (which are reasonably standard) are:

Out of work through no fault of your own

Physically able to work

Actively seeking work

Ready to accept work

Failing a physical probably meets the "through no fault of your own" requirement, possibly depending on the reason you failed. If you failed it because of the results of a drug test, for example, that's pretty much your fault.

Also, the "physically able to work" might be impacted, depending on exactly why you failed the physical.

Your best bet is to go ahead and apply unless you're absolutely certain you don't meet your state's eligibility requirements (your state probably has a website where you can check the requirements; most likely you'll be able to apply there also). If it's an iffy case, the state will probably call you and your former employer (separately) to discuss your situation, and then either allow or deny your claim.