Antielectron

The question: Boy saw a ball first moving up and then down past an open window. The top-to-bottom height of window is 2.00m. Ball in view for a total duration of 0.50s. Calculate how much further above the window top did the ball move before reaching its highest point. [acceleration due to gravity = 10ms^-2 and ignore air resistance]. Answer is given, but i am unable to solve it. Tried using 1/2mv^2 and mgh etc., but still unable to. Anyone out there who knows...?

Thanks a lot for ur help, it was useful

Thanks for that =D So it becomes 0.0512dm3 , 0.00213mol and 0.60918kJ for the first half....

I have a science project and I have decided to find out if the amount of energy (joules) produced when combustion of hydrogen gas in air takes place. I need someone to check if there are any problems, and here is what I worked out: Volume of Hydrogen gas (H2)collected: 51.2cm3 = 0.0000512dm3 No. of moles of H2= Volume/Molar Volume = 0.0000512/24 (at rtp) = 0.00000213mol Enthalpy of Combustion forHydrogen: -286 kJ/mol Energy produced: 286 kJ/mol x 0.00000213mol = 0.00060918kJ (H2) I'm also comparing it with 10 x 9volts battery, which also requires me to calculate the energy (joules) produced... Battery (Eveready 9 Volts): 325mAh = 0.325 Ah Energy produced: IV = Js-1 90(0.325) = (200 x 60)-1J (in 200minutes) 29.25 = 12000-1J J = 351000 351000J = 351kJ ∴Energy (Battery) > Energy (combustion of Hydrogengas) Looks flawed to me, and assuming that the battery have a constant mAh throughout. Would be glad for any help given, thanks!