One model of tennis ball launcher has advertised that it is capable of imparting 15,000 J of kinetic energy to a 0.5 kg ball initially at rest. A student carefully measures the compression of the spring to be 0.10 m. What is the value of the spring constant for the tennis ball launcher according to the data provided?

If you visited mount shasta city (elevation 900 m [3000 ft.]) and found the outside air temperature to be 27°c (81°f), what would be the air temperature at the summit of mount shasta (elevation 4200 m [14,000 ft.]) at that moment-assuming that the temperature conditions with altitude change at an average, or normal, lapse rate?