Ek - kinetic energy v2 - unknown speed v1 - 40 m/s (initial speed) Ek=1/2 mv^2 Ek in half way up is 1/2 Ek (with another V) So, Ek in the beginning is Ek1= 1/2 mv1^2 and in half way Ek2=1/2 mv2^2 Ek1=2*Ek2 1/2 mv1^2 = 2* 1/2 mv2^2 1/2 v1^2 = v2^2 1/2 40^2 = v2^2 800 = v2^2 v2 = sqrt (800) = 28,3 m/s
