It takes a force of 28,888 lb to compress a coil spring assembly from its free height of 9 inches to its fully compressed height of 5 inches. a. What is the assembly's force constant? b. How much work does it take to compress the assembly the first half inch? the second half inch? Answer to the nearest in-lb. a. k= 7222 lb/in b. How much work does it take to compress the assembly the first half inch? in-lb (Round to the nearest whole number as needed.)