5. In the table, record the static force used to stretch the spring. This is merely equal to mg, where m = 0.550 kg 6. Detach the mass hanger from the string and wind the string around the top of the suspended mass so that it is not in the way when things start spinning. You will now need to manually rotate the system by using your ngers to turn the bottom portion of the rotating post, where there are grips for traction. Continue to increase the rotation rate of the system until the bottom tip of the suspended mass is pas sing directly over the top of the measuring post. This particular motion must then be sustained by whoever is turning the post. You should be eye level with the tip of the measuring post and directly in front of it so that you can determine when the rotating mass is going directly of the tip of the post. Failure to do this all properly will result in you doing it over again. 7. Using the measuring post for reference, start a timer and begin to count each full revolution of the suspended mass. Start the timer just as the suspended mass reaches the measuring post and then the next time it reaches the post you will have 1 revolution. Count off 60 full revolutions and stop the timer once the last one is reached. The timer then reads the amount of time it took to complete 60 revolutions. Record the time in the table and use it to determine the angular velocity of the suspended mass in radians per second. 60 Rev = 120a radians. The angular velocity, co, is then 12011: radians divided by the time it took. 1. Detach the suspended, tear-shaped mass from the system and determine its mass in kg. 2. Reattach the mass and proceed by setting up the system as show above. In the diagram the spring is not stretched at all and lays level with the base. Note that the suspended mass is hung by a string and it is completely vertical. The Rotating arm must be adjusted so that this is the case. Loosening the wing nut at the top of the rotating post allows for the arm to be slid from side to side. Upon positioning the arm in the proper location, adjust the counter balance such that arm is balanced evenly. After this is done the wing nut may be secured, preventing the arm from moving out of place. 3. The base of the apparatus may also need to be leveled. This is done by placing the rotating post at different locations and seeing if it tends to rotate on its own. If it does, the 3 black knobs on the base are used to lower or raise a particular portion of the base. When the system will remain at rest at any location it is ready to use! 4. Now attach a mass hanger to the string that is secured on the side of the suspended, tear-shaped, mass and position it over the pulley. Apply 500 grams of mass to the hanger and notice that the spring has now stretched. The suspended mass will again need to be positioned so that the string suspending it lay completely vertical. To do this adjust the rotating arm and again move the counter balance to equalize the torque on either side of the arm. Once the arm is situated properly, adjust the height of the pulley so that the string that runs over the top of it is completely horizontal. Also, move the measuring post so that it is directly below the bottom of the suspended mass. The conguration is shown in the following diagram. Repeat the general procedure using a load of 650 grams. Table #- 650 g static mass Static Force Exerted by the Spring Time to Complete 60 Revolutions 00:40: 47 Angular Velocity of the Rotating Mass Radius of Rotation for the Rotating Mass 0 . 154 meters Mass of the Rotating Mass 0 - 449 kg Centripetal Force Exerted on the Rotating Mass %-Difference Between the Static and Centripetal ForcesRepeat the general procedure using a load of 750 grams. Table #- 750 g static mass Static Force Exerted by the Spring Time to Complete 60 Revolutions 00: 38:76 Angular Velocity of the Rotating Mass Radius of Rotation for the Rotating Mass 0 . 162 meters Mass of the Rotating Mass 0 . 449 kg Centripetal Force Exerted on the Rotating Mass %-Difference Between the Static and Centripetal ForcesRepeat the general procedure using a load of 850 grams. Table #- 850 g static mass Static Force Exerted by the Spring Time to Complete 60 Revolutions 00:37: 50 Angular Velocity of the Rotating Mass Radius of Rotation for the Rotating Mass 0. 171 meters Mass of the Rotating Mass 0 . 449 kg Centripetal Force Exerted on the Rotating Mass %-Difference Between the Static and Centripetal ForcesRepeat the general procedure using a load of 950 grams. Table #- 950 g static mass Static Force Exerted by the Spring Time to Complete 60 Revolutions 00: 36:27 Angular Velocity of the Rotating Mass Radius of Rotation for the Rotating Mass 0 .179 meters Mass of the Rotating Mass 0 . 449 kg Centripetal Force Exerted on the Rotating Mass %-Difference Between the Static and Centripetal ForcesPhysics 101-121 Lab #11 Centripetal Force In this lab we will look at the force responsible for keeping an object constrained to a circular path, the centripetal force. A mass attached to the end of a spring will be rotated by use of a rotational inertia apparatus. As the mass rotates in a circular manner, a centripetal force is exerted on it by the spring. The spring force is thus responsible for constraining the path of the mass. For a rotation that is at a constant rate we will have that the centripetal force is constant, resulting in a circular path. As the mass rotates at a constant rate, the spring is stretched by some amount and continually pulls the mass inward with a constant force. Having the spring stretched by the same amount due to a known static force, we seek to verify the validity of the expression used to determine the centripetal force. F c 2 mm)2 This lab Will be run by the instructor and you will take time measurements for the rotation rate. See parts 7, 8, and 9. Using the Apparatus Counter Balance Puriey 8. Measure the distance from the tip of the measuring post to the center of the rotating post such that you have the radius at which the center of the suspended mass rotated with. 9. Recall that the centripetal force acting on an object in uniform circular motion is constant in magnitude, F=mro; where m is the mass of the suspended object, r is the radius of rotation and w is the angular velocity of the suspended mass. Calculate and record this value below. Also calculate the %-difference of Fc with the force due to the static load used to first stretch the spring. If your results yield a %-difference greater than 7%, you will need to repeat that part. Calculate one system at a time so that if there is a problem you can easily run it again, and/or identify what the issue is. 0. 449 kg Table #1- 550 g static mass Static Force Exerted by the Spring Time to Complete 60 Revolutions 60: 42:82 Angular Velocity of the Rotating Mass Radius of Rotation for the Rotating Mass 0. 144 meters Mass of the Rotating Mass 0 . 449 kg Centripetal Force Exerted on the Rotating Mass %-Difference Between the Static and Centripetal Forces