Homework 1/16/03

Period 1 - Have a nice long weekend. Bring your work from the semester to school in preparation for portfolios next week. Period 2 - Musical Instrument Challenge presentations on Friday. Portfolios next week. Period 3 - Musical Instrument Challenge presentations on Friday. Portfolios next week. Period 5 - Complete Projectile Challenge Lab in class on Friday and prepare poster and one-page report for Tuesday. Period 7 - Force & friction problem set 1 due on Wednesday, JAn 22. The three questions are reprinted below for your reference. ============================= Instructions: -Draw FBDs for all problems. -Show all of your work. -There will be a 1 question quiz Wednesday, 1/22, with a problem similar to these. That problem will be added to this problem set and the 4 problems together will be graded as one sample of work. 1. At Sea World, a 900-g Polar Bear slides down a wet slide inclined at an angle of 25º to the horizontal. The coefficient of friction between the bear and the slide is 0.050. What frictional force impedes the bear's motion down the slide? 2. In the design of a supermarket, there are to be several ramps connecting different parts of the store. Customers will have to push grocery carts up the ramps and it is desired that this not be too difficult. An engineer has done a survey and found that almost no one complains if the force required is no more than 50N. Will a slope of 5º be too steep, assuming a 30-kg grocery cart? Assume friction (wheels against ground, wheels on axles, etc.), can be accounted for by using a coefficient of 0.10. 3. A 22-kg child slides down a slide with a 28º incline, and at the bottom her speed is exactly half of what it would have been if the slide was frictionless. Calculate the coefficient of kinetic friction between the slide and the child.