Extremely hard physics questions...with answers...but plz show how u got answer...i couldn't get these ones...

1. Joe has developed hollow spherical barges to transport cargo through the great lakes without danger of running aground. The shell of one barge is made of thin steel plate with a mass per unit area of 100 kgm^-2 and its radius is 3 m. It is loaded with iron pyrites having a density three times that of water and... show more 1. Joe has developed hollow spherical barges to transport cargo through the great lakes without danger of running aground. The shell of one barge is made of thin steel plate with a mass per unit area of 100 kgm^-2 and its radius is 3 m. It is loaded with iron pyrites having a density three times that of water and it floats exactly half submerged. How much cargo is there? answers in meg grams = tonnes...(a) 45.2 (b) 15.1 (c) 90.5 (d) 56.5 (e) 11.3

2. A particle of mass m rests upon a rough horizontal plane with a coeffiecient of kinetic friction mu=1/4 and is connected by light elastic strin, with elastic constant k, to a fixed point, P, in the plane. If the string is just taut find the initial speed, V, that the particle needs if it is projected directly away from P such that it just returns to its inititial position. a) g√(m/2k) b)g√(6m/k) c)g√(2m/k) d)g√(m/k) e)g√(k/m)
Update: these questions even stomped teacher!!
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