9. If you throw a ball up into the air with an initial vertical velocity of 50 m/s, how long will the ball be in the air before it comes all the way back down to your hand?

In a particular chemical reaction, the energy of the reactants is 30 kj and the energy of the products is 5 kj. 
 the maximum energy of the system is 40 kj. sketch a potential energy diagram for this reaction. make sure to label the energy of the reactants, the energy of the products, the activation energy, and the enthalpy change for the reaction.