Question

Hi friends ,

A girl is carrying a school bag of 3 kg has the same diameter as an aluminum sphere of mass 3.5 kg.Both the spheres are dropped simultaneously from a tower .When they are 10m above the ground ,they have the same::

a.6000 J
b.0.6 J
c.0 J
d.6 J

Answer 1

actually, 
    workdone is the product of force and displacement along force . 

here we see a girl carrying a school bag then, dropped simultaneously. it means displacement of body = zero [ because body move equal distance in opposite direction.] 
hence, net workdone during motion = force . displacement 
                                                            = force . zero  
                                                            = zero
now, here we see that , no external force act on bag.
so, total energy = - workdone 
                           = 0J
hence, total energy of both have same e.g zero.
[ actually, potential energy manage the kinetic energy . that's why total energy = PE + KE = 0]

Answer 2

Answer:

Answer is Option C - O joules..

Hope it helps!!!