You have 9 stones that are identical in appearance. one of these stones weighs just a bit more than the other 8. these other 8 stones are exactly the same in weight. using a balance scale only twice, how can you determine exactly which stone is the heavier?

Atomic nuclei of almost all elements consist of

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.

What kind of simple machine is a catapult?