Grace+Carroll+2-2-09

On February 2, 2009 I sat in on Mr. Manning’s Physic’s class. The first thing he did in class was collect the homework, which was where the students had to complete a worksheet containing the 10 commonly missed questions on the 2008/2009 midterm. After collecting the midterm worksheet, he checked our second worksheet that was for homework. We reviewed this page, (page 6) which had to do with solving problems based on diagrams, force and power. One of the force problems was asking us to find how much work was being done on a 110 kg mini-car while one pushes it with a horizontal force of 500N for a distance of 20 meters. To solve this, the students used the equation for work, which was Work=Force multiplied by the change in x multiplied by. The force given was 500N, the change in x was 20 meters, and there was no angle given, so the would just be written as  0. After multiplying 500 N and 20 meters, we found out the work done on the mini-car was 10,000 J. (J is the unit that work is measured in, which stands for Joules). Another type of problem we had to solve was a power problem. Before we solved a power problem though, we had to know what the work was. One of the problems had a work of 3,675 J, and with that information as well as the information given in the problem, we could solve for power. We had to solve how much power was expended for this using the work of 3,675 J and the given time of 2.1 seconds. The equation for power is work/time, so in order to solve this, we divided 3,675 J / 2.1 seconds to get the power to equal 1,750 W (watts). The students also reviewed their lab from the previous week, which was on page 8. In the lab the students had to decide which scenario would require more work to be done; lifting a box straight up at 90 degrees, pulling a box up a short ramp at 40 degrees, or pulling a box up a long ramp at about 15 degrees. Our class calculated the work done for the straight ramp, which was 1.800 Netwon times meters, the short ramp, which was 1.861 Newton times meters, and the long ramp, which was 1.917 Newton times meters. All of the ramps required pretty much the same amount of work to be done because the mass and acceleration of the cart wasn’t changed, only the angle was changed. After reviewing the lab, the students received a worksheet, page 10. On the worksheet the students had to solve more work and power problems. One of the questions asked how much work was needed to lift an object that weighed 200 N to a height of 4 meters. The amount of work needed was 800 Joules, and we solved that by multiplying 200 Netwons times 4 Meters. After the worksheet, the students completed the daily question, which was given at the end of the period instead of the beginning. They had to solve how much work is done when a mechanic uses a jack to lift a car that has a mass of 1000 kg, to a height of 2.5 meters. Using the work formula, the students multiplied the force of 1000 kg times the change in x, which was 2.5 meters to get the work to be 2500 J. After we found the work, we had to find the power, with a given time of 8 seconds. When we divided 2500 J / 8 seconds, we found out the power to be 312.5 W. I was glad I experienced another day in Mr. Manning’s Physic’s class, and I’m looking forward to my next visit and to learn more!