Re: [Phys-L] Tennis Ball on Basketball

[bernard cleyet <bernardcleyet@redshift.com>]

> On 2017/Feb/23, at 09:19, John Denker via Phys-l <phys-l@mail.phys-l.org> wrote:
>
> > the timing does matter.
>
> Absolutely it matters.
>
> Related fun factoid:  In an ordinary Newton's Cradle device, the
> balls at rest are *not* touching ... for exactly this reason.
>
> Rather than solve the general case, which is more work than I
> feel like doing at the moment, I suggest rephrasing the question.
> Simply /require/ that the two balls be slightly separated.


Philip at N. Salinas High uses a coin on the ball.  Works well.  No separation there.  


A reasonable height is one meter.  So speed ~ 4.4 m/s  (E principle easier than kinematics)   Re then ~  69k,   therefore, Cd ~ 0.5  

Drag then  v. ~  0.55N    Mass of basket ball ~ 0.625   force then v. ~  6N  so ignorable (treat as free fall)  E at impact v. ~ 6 J.  

If coefficient of restitution v. ~ 0.85  then initial speed after impact is ~ 3.74 m/s  

mass one cent  2.5 g     momentum principle  > 900 m/s   


bc amateur physicist and thinks something wrong there.  

done v. hurriedly