insect on the insect!!!!!!

Classical Mechanics Level 5

A drinking straw of length 1.5 a 1.5a and mass 2 m 2m is placed on a square table of side a a parallel to one of its sides such that one third of its length extends beyond the table. An insect of mass m 2 \frac{m}{2} lands on the inner end of the straw (ie, the end which lies on the table) and walks along the straw until it reaches the outer end. It does not topple even when another insect lands on top of the first one. Find the largest mass of the second insect that can have without toppling the straw. Neglect friction. Take m = 0.02 k g m =0.02kg a = 1 m a =1m


The answer is 0.1.

Abdulmuttalib Lokhandwala by abdulmuttalib lokhandwala , 23

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1 solution

When the insect went from one end to another the end the net force on the system ( s t r a w + i n s e c t ) (straw +insect) is 0 . So the centre of mass of the system remains at the same position i . e i.e it doesn't get displaced. So when insect goes further the straw moves somewhat backwards so find the final position of the straw. Now when the another insect sits on the first one the straw will not topple till the centre of mass of the system just comes at one end of the square plate so find the mass of this insect such that its centre of mass just come at its end.solving for it you will get mass of the insect to be 5 m 5m

7 Helpful 1 Interesting 1 Brilliant 0 Confused

N e g l e c t Neglect F r i c t i o n Friction Is the main thing should consider

Kelvin Hong - 3 years, 5 months ago

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Friction needs to be neglected only between the straw and table, since friction between straw and insect is an internal force, it does not displace the center of mass of the system.

Harsh Poonia - 1 year, 9 months ago

I was confused how insect reached other end even if friction is neglected.

Kunwar Pratap Singh - 3 years, 4 months ago

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Friction needs to be neglected only between the straw and table, for the insect to reach the other end, friction should be present between insect and straw. Of course, that does not affect our argument since the Net External Force , F ⃗ ext = 0 \text{Net } \textbf{External Force}, \vec{F}_{\text{ext}}=0 still.

Harsh Poonia - 1 year, 9 months ago

1 pending report

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