g = 9.8 N/kg A 2.5kg ball is thrown directly upward and it r…

g = 9.8 N/kg A 2.5kg ball is thrown directly upward and it reaches a height of 15m before it starts to descend.  Using mechanical energy, solve for.. a) The speed that it was initially thrown with.   b) It’s speed when it is 40% of the way to the top of its flight.