two.two.09

Today in the wonderful world of physics, Mr. Manning first walked around the room and checked to make sure the students completed the Work and Power Worksheet (page 6) and collected the Top 10 frequently missed questions worksheet for a total of 10 points. Looking up at the board I read what was in store for today. It read the following: Homework check, Review Homework, Review Lab, Worksheet, and Suprise!. I remember thinging, I wonder what the suprise could be? As the class went on we went over the answers to page 6 ( Work and Power Worksheet) by having one person read the question and then provide an answer also. We then went over last Friday's lab, Working on the Ramp Lab (page 8). In a class discussion we were able to come to the conclusion that they were all relitively close in answers, but lifting a box straight up at a 90 degree angle would require more work to be done. This made me pretty happy because it ment that my prediction was correct. Many people, along with myself, forgot to check the front desk for any handouts. Page 10 was to be found here, Chapter 7 Energy. We were to complete this page during class time, which was not to difficult, and then as a whole go over the answers. Finally we got to the suprise time, which I had been waiting all class period for. What a suprise indeed, thinking outside the box there Mr. Manning :). NO, it was nothing more then a graded daily question, but hey no complaints because I always manage to miss the ones in the very beginning anyway. Finally the bell rung and we all scurried out like a bunch of field mice. The End.

1.How much force is needed to push the box up the incline? 1500 J/ 6m = 250 N 2.How much work is required to push the box up the incline compared with lifting the block vertically 3 m? 3m * 500 N= 1500J

Practice Problems to try for yourself :D Work and Power Worksheet: 3. d.) How much work is done on the 250 kg BATCYCLE while it is sitting on the hydraulic lift 2 meters high during repairs? 4. a.) How much power is expended in 3a (4900 J) if it took 1.6 s to lift the barbell?

Chapter 7 (Energy): 1. How much work (energy) is needed to lift an object the weighs 200 N to a height of 4m? 2. How much power is needed to lift the 200 N object to a height of 4 m is 4 s?

Answers: d.) 0 Joules...why?...because it is __sitting__ on the lift, it has no displacement. a.) Power = work divided by time....4900 J divided by 1.6 s = 3100 W (watts) 1. 200 N X 4 m = 800 J 2. 200 N X 4 m / 4 s = 200 W