posted by Bob .
A box weighing 5kg sits on a box weighing 10kg. The static friction between them is .5. There is no friction under the bottom box. How much tension is needed on the bottom box to make the top box slide?
I assume you mean the static coefficent of friction is .5
Given that, then the force of friction static on the top box is .5(5)g max. over that, and it slides.
Now to achieve that acceleration, then