Lab 5 Pendulum

Lab 5 Pendulum Lab Objective To understand the pendulum as it demonstrates simple harmonic motion. We will test the effects of length, mass, and starting angle on the period of a pendulum. Materials  Lab Stand  String (75 cm long)  Hooked mass set  Meter stick  Stopwatch  Tape measure  Protractor Since this is an online lab, watch “Pendulum - Data Collection Video: and record the data in Tables 1, 2 & 3 below. To understand the pendulum as it demonstrates simple harmonic motion. We will test the effects of length, mass, and starting angle on the period of a pendulum. Since this is an online lab, watch “Pendulum - Data Collection Video: and record the data in Tables 1, 2 & 3 below. Data Collection Video Link: https://www.youtube.com/watch? v=ZFJuJx1MWiw Demo: https://www.youtube.com/watch?v=z6ZdhP167RY  Lab Stand  String (100 cm long)  Hooked mass set  Meter stick  Stopwatch  Tape measure  Protractor A Mass m suspended by a wire of length L is a simple pendulum and undergoes simple harmonic motion. The period of a simple pendulum is, T T = 2 π √ L g where L is the length of the string and g is the acceleration due to gravity.

Angle 1. Hang a 50 g mass from the lab stand with a string that has a length of 0.75 m. Measure the length from the pivot point to the center of gravity of the mass. 2. Pull the pendulum upward so that the string makes an angle of approximately 15  from vertical. 3. Release the pendulum and start the stopwatch. Record the time required for 10 complete oscillations of the pendulum in Data Table 1. 4. Repeat steps 2 and 3 for angles of 30  & 45  . Mass 1. Hang a 50 g mass from the lab stand with a string that has a length of 0.750 m. Measure the length from the pivot point to the center of gravity of the mass. 2. Pull the pendulum upward so that the string makes an angle of approximately 15  from vertical. 3. Release the pendulum and start the stopwatch. Record the time required for 10 complete oscillations of the pendulum in Data Table 2. 4. Repeat steps 2 and 3 100 g and 200 g. Length 1. Hang a 100 g mass from the lab stand with a string that has a length of 0.25 m. Measure the length from the pivot point to the center of gravity of the mass. 2. Pull the pendulum upward so that the string makes an angle of approximately 15  from vertical. 3. Release the pendulum and start the stopwatch. Record the time required for 10 complete oscillations of the pendulum in Data Table 3. 4. Repeat steps 2 and 3 for lengths 0.50 m and 0.75 m. Data Data Table 1 Mass 5 points MASS TIME Experimental Period (T) Theoretical Period (T) Percent Error 15  17.22 1.722 T = 2 π √ L g T = 1.74 1.034% 30  17.02 1.702 2.184% 45  17.34 1.734 0.344% Data Table 2 Angle 5 points MASS TIME Experimental Period (T) Theoretical Period (T) Percent Error 50 g 17.27 1.727 T = 2 π √ L g T = 1.74 0.747% 100 g 17.62 1.762 -1.264% 200 g 17.83 1.783 -2.471% Data Table 3 Length LENGTH TIME Experimental Period (T) Theoretical Period (T) Percent Error 0.50 m 14.10 1.410 1.41 0%

Questions 3 points Answer the following post-lab questions. See “Good Lab Practices” on page 1. 1. Discuss your graph of “Period versus Mass”. What dependence does the period have on mass? time is dependent on the mass of the string. 2. Discuss your graph of “Period versus Angle”. What dependence does the period have on the angle? Is there a specific point where the period becomes dependent on the angle? What is the significance of this angle? There is no dependence the period has on the angle, only the length of the string. The length of the string means the longer time of the pendulum has to complete an oscillation 3. How close is your calculated acceleration due to gravity to the actual value that you expect? Explain any differences. The acceleration of gravity is 9.8 m/s^2