A tennis ball (2 kg) is traveling West at 4 m/s. It is hit by a racquet for 0.01 s and flies off at 4 m/s East. How much force is exerted and in what direction?

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.