Physics - Rotation Question with Solution | TestHub
A tall tower is built from alike tubes with thin walls, and from rectangular sheets whose mass is negligible compared with the tubes, as shown in the figure. The sheets are numbered from bottom as S1, S2, S3, ... . Static friction is large enough that the tubes do not slip. Each tube has radius 1 cm.
The minimum distance by which should be pulled towards right so that the tower collapses is :
Options:
Answer:
Solution:
Because the tubes roll without slipping, when the sheet is pulled out by a distance , the tubes resting just below it and just above it each shift horizontally by (a roller between two surfaces moves at half the relative speed of the surfaces), while all the other tubes remain in their original places. The centre of gravity of the part of the tower above these tubes is therefore displaced relative to its support by . Since the sheets are 20 cm wide, the displaced centre of gravity reaches the edge of its base -- and the tower collapses -- when the sheet is moved by a distance greater than 5 cm. Hence the minimum distance is 5 cm, answer (D).
