Answer:
m2 = 83.3 g
Explanation:
by conservation of momentum principle we have

as both sphere has same speed so 

from conservation of kinetic energy principle we have




substituting this value in above equation to get m2 value

solving for m2 we get

m_1 = 250 g

m2 = 83.3 g
No because it is dense and opaque
Resonance, Because its another way of saying sound waves. It determined the objects frequency.
1 gives the process something to prove or disprove. Famous examples .... Einstein vs newton, Hawking vs steady state universe theories
you set the ind variable. convenient numbers help.
dep var follows according to theory/hypothesis ...
experiments and theories must repeat, and be same for anyone N pole to S pole etc