What is the change in the total potential energy of the spring-mass-earth system (the horizontal rod is fixed, eventually, to the earth) as the mass moves the 21.0 cm upward from its release point? also, what is the speed of the mass after it has moved upwards by 21.0 cm from its release point?

D.haka is the first answer and a.canberra is the second answer

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen