Objectives for Lab 3 (Free Body Diagrams, Circular Motion). Prove that forces are vectors and understand the difference between externally applied forces and internal reaction forces. 11 Explore uniform circular motion. Conduct an experiment to understand centripetal force and centripetal acceleration. 21 Procedure for objective # 1. Suspend a block on a string in a vertical position. Let one member of a team pull the block to the right. a) Draw a free body diagram of the block. In which direction did the block move ? Why did the block move in that direction ? Suspend a block into a vertical position again. Let one member of a team pull the block to the right, while another member of a team pull the block b) Draw a free body diagram of the block.. In which direction did the block move ? Why did the block move in that direction ? Is it possible the block not to move while both people are pulling on it? Why? c) Based on your observations in parts a) and b), explain why force is a vector. a string that supports the block in the vertical suspended position. The block is not moving. Now co d) Draw a free body diagram of the string. Is there a net external force on the string? Procedure for objective 2): a) Suspend a known mass from a cable (with a force meter attached to the cable) and let the mass hang vertically. b) Extend your arm and using your wrist, start rotating the mass suspended from the cable. c) Record reading of the force meter. d) Estimate radius of the formed circular motion and the angle that a cable makes with the vertical axis. e) Estimate the time required for the mass to complete one revolution Assuming uniform circular motion, calculate tension in the cable and compare it to tension of the cable read by the force meter. Assuming uniform circular motion, calculate tangential velocity of the mass using values from part d) above. Use estimated time from calculate tangential velocity of the mass. Compare the two values of tangential velocities (Use solved problem 5.19 for a reference) I. II. Lab report: Summarize answers to the problems above using an "Laboratory Report Format".