Counter Balance HIM 1. Reference the diagram shown regarding the apparatus. 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 moved 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. 2. 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! 3. 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 is 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 if needed 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 configuration is shown in the following diagram. Repeat the general procedure using a load of 750 grams. 60 Revolutions Table #2- 750 g static mass Constant angular velocity Angular Displacement 120n Radians Time 1 00:38:61 Time 2 00: 38:53 Time 3 00:38:85 Angular Velocity 1 Angular Velocity 2 Angular Velocity 3 Average Angular Velocity Angular acceleration- Light Pinch Time to Stop 00: 05: 35 Initial Angular Velocity Angular Acceleration Angular acceleration- Medium Pinch Time to Stop 160:03:04 Initial Angular Velocity Angular Acceleration Angular acceleration- Strong Pinch Time to Stop 00: 01:17 Initial Angular Velocity Angular Acceleration6. Next you will again make the mass rotate such the bottom of it passes over the measuring post. Once it is up to speed, gently \"pinch\" the rotating post with your thumb and index nger. Try to sustain a constant pressure with your pinch. You will measure the time it takes the apparatus to stop rotating once it is at it full speed. Using your average angular velocity from the preceding part as the initial angular velocity along with your measurement of time to stop, you will then calculate the object's angular acceleration using the equation of motion for constant angular acceleration. Repeat this with a medium pinch pressure and then a relatively strong pinch. 7. Repeat the general procedure for the different rotational rates needed; determined by the static system. Rotational Motion In this lab we will look at some of the aspects regarding quantifying rotational motion such as angular displacement, angular velocity, and angular acceleration. We will measure the time it takes an object rotating at a constant rate to complete a number of full revolutions. This can then be used to determine the angular velocity of the object as it was rotating. We will also produce a resistive force on the object to make it come to a stop, measuring both the time and angular displacement over this interval. This data will then be used to determine the angular acceleration of the object as it comes to rest. Below is an explanation of the setup and procedure. I will be running the apparatus in a video and you will make time measurements in the convenience of your own location as outlined in part 5 and 6. Safety- The apparatus used in this lab has parts that rotate. Long hair should be kept clear of the moving parts. Be certain that care is taken in its operation and watch your hands, face and ngers! Using the Apparatus Tables #1- 550 g static mass 60 revolutions Constant angular velocity Angular Displacement 120nt Radians Time 1 00: 45: 50 Time 2 60 : 42:48 Time 3 00: 43:08 Angular Velocity 1 Angular Velocity 2 Angular Velocity 3 Average Angular Velocity Angular acceleration- Light Pinch Time to Stop 00:08: 68 Initial Angular Velocity Angular Acceleration Angular acceleration- Medium Pinch Time to Stop 06:03:86 Initial Angular Velocity Angular Acceleration Angular acceleration- Strong Pinch Time to Stop 00: 01: 37 Initial Angular Velocity Angular AccelerationRepeat the general procedure using a load of 950 grams. Table #3- 950 g static mass Constant angular velocity Angular Displacement 120n Radians Time 1 60: 36:00 Time 2 100 : 36:80 Time 3 00: 36:50 Angular Velocity 1 Angular Velocity 2 Angular Velocity 3 Average Angular Velocity Angular acceleration- Light Pinch Time to Stop 00 : 08: 19 Initial Angular Velocity Angular Acceleration Angular acceleration- Medium Pinch Time to Stop 00 : 04: 10 Initial Angular Velocity Angular Acceleration Angular acceleration- Strong Pinch Time to Stop 00:01: 45 Initial Angular Velocity Angular Acceleration4. Now 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 fingers to turn the bottom portion of the rotating post, where there are grips for traction. Continue to increase the rotational rate of the system until the bottom tip of the suspended mass is passing 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. 5. Using the measuring post for reference, you will 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 = 120n radians. The angular velocity, @, is then 120n radians divided by the time it took. Repeat this 3 times and then take the average value of the angular velocity