9. You go to the gym 5 times a week, and each time you are there you bench press 80.0kg thirty times. Each time you are lifting the barbell basically the length of your arm (about 0.80m). a. Over the course of a year, estimate how much total work (in Joules) you've done on the barbell while lifting it upwards. b. If all of this energy were instead used to accelerate a tractor trailer (mass 20,000kg ), what speed would it attain?