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The Bricklayer's Lesson in Physics Physical Science Motion and Machines Grades 9 to 12 Object of the Lesson: To creatively review various forces acting on objects in motion. Student Directions: Read the following report, written to an insurance company as explanation for a claim of medical benefits. Make a list of the five collisions which resulted in this man's injuries. For each collision, make a second list of the forces involved which caused the injury. For extra credit, design a pulley which would prevent this bricklayer from being lifeted off the ground by 500 lbs. of bricks. Explain why it works. Dear Sir, I am writing in response to your request for additional information. In block number three of the accident reporting form, I put "poor planning" as the cause of my accident. You said in your letter that I should explain more fully, and I trust that the following details will be sufficient. I am a bricklayer by trade. On the day of the accident, I was working alone on the roof of a six-story building. When I completed my work, I discovered that I had about 500 pounds of brick left over. Rather than carry the bricks down by hand, I decided to lower them down in a barrel by using a pulley which, fortunately, was attached to the side of the building at the sixth floor. Securing the rope at ground level, I went up the roof, swung the barrel out and loaded the brick into it. Then I went back to the ground and untied the rope, holding it tightly to insure a slow descent of the 500 pounds of brick. You will note in block number eleven of the accident reporting form that I weigh 135 pounds. Due to my surprise at being jerked off the ground so suddenly, I lost my presence of mind and forgot to let go of the rope. Needless to say, I proceeded up at a rather rapid rate up the side of the building. In the vicinity of the third floor, I met the barrel coming down. This explains the fractured skull and broken collarbone. Slowed only slightly, I continued my rapid ascent, not stopping until the fingers of my right hand were two knuckles deep into the pulley. Fortunately, by this time I regained my presence of mind and was able to hold tightly to the rope in spite of my pain. At approximately the same time, however, the barrel of bricks hit the ground and the bottom fell out of the barrel. Devoid of the weight of the bricks, the barrel now weighed approximately 50 pounds. I refer you again to my weight in block number eleven. As you might imagine, I began a rapid descent down the side of the building. In the vicinity of the third floor, I met the barrel coming up. This accounts for the two fractured ankles and the lacerations of my legs andlower body. The encounter with the barrel slowed me enough to lessen my injuries when I fell onto the piles of brick, and fortunately, only three vertebrae were cracked. I am sorry to report, however, that as I lay there on bricks--in pain, unable to stand, and watching the barrel six stories above me--I again lost the presence of mind-- I LET GO OF THE ROPE--