# tough physics

posted by
**Steve**
.

A boy is spinning on a chair and holding a paper bag so that it is horizontal, and perpendicular to the axis of the rotation. What should be the angular velocity of the boy in radians/second so that the bottom of the bag breaks?

Details and assumptions

Assume paper breaks at an overpressure of 1.2 atm.

The molecular mass of the air is 29 g/mol.

The boy's arm is L=70 cm long.

When horizontal, the bag has a shape of a cylinder of length 30 cm.

Outside pressure is 1 atm and temperature 25 degrees C.

Assume that the boy won't get sick no matter how fast he is spinning. Hint: he whizzes around.