## salini 3 years ago Boy and girl sailing on a boat(the boat mass is:25 kg), the boy mass is: 95kg and mass of the girl is smaller from boy When the boat was at rest in quiet water the boy ang girl exchanged their place. Both were symmetrically about the center of the boat and the distance between them was 3.0 m After they switched place the guy saw thet boat moved at 40cm relation to log which was beside of the boat, What is a girl's mass?

1. hosein

Hi you can solve this by relation of displacement center of mass

2. chand

sum of moments of masses about the centre of mass is equal to zero. you can use this concept

3. salini

i am not able to understand that 40cm displacement part does the entire boat get displaced in the horizontal direction by 40cm they interchanging the places changes the com but how does the 40cm move inthe horizontal plane account for it?

4. salini

how can we relate the two?

5. Taufique

|dw:1333300411963:dw| |dw:1333300529345:dw| Let the mass of the girl be M;here no external force is present,hence the centre of mass of the system be conserve: (C.O.Mass)initial=(C.O.Mass)final 95*(-1.5)+25*0+M*(1.5)=95*(0.4-1.5)+25*0.4+M(0.4+1.5) find the M which give you the mass of the girl...

6. salini

that is nice the co-ordinates of my chosen origin change but not the com thank u all for ur responses