Posted by Alex on Friday, August 31, 2012 at 3:30pm.
Use the equations:
S=vi*t + (1/2)gt^2
For 1st ball:
20=0+(1/2)gt^2 => t=sqrt(40/g)
For 2nd ball:
20 = vi*(t-1) + (1/2)g(t-1)^2
vi = [20-(1/2)g(t-1)^2]/(t-1)
=(20-(9.81/2)*(t-1)^2)/(t-1)
=14.62 m/s downwards
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