Procedure J 1. Carefully level the air track by turning the white plastic screw on its base, and using the gliding cart as an indicator of slope. 2. Measure the mass of the glider and the length of the glider that trips the photogate timer. 375 stut fr 80 cm / 3. Attach a string to the glider, drape it over the pulley at the end of the air track. Tape a 10 gram flat weight on top of the glider, and attach a 10 gram hanging weight to the other end of the string. The string's length should be such that when the hanging weight is suspended 80.0 cm above the floor, the glider is near the far end of the air track. J4. Position the photocell timer anywhere past the point where acceleration ends - the hanging weight has reached the floor - but not so close to the end of the track that the glider will bounce back through it. 5. Release the glider from rest and stop it before it can bounce back through the photocell timer. 6. Record the time under ti in Case I. Repeat step 5 two more times, and record the times under t2 and t3 for Case I. N7. Case II: Remove the 10 gram flat weight from the glider and replace the gram hanging weight with a 20 gram hanging weight. NOTE: Since the different weights are of different lengths, the position of the glider when the weight has exactly 80.0 cm to fall may change slightly. Account for this carefully. 10 /8. Measure and record the time three times as in the previous case. 9. Use Eq. (1) to calculate the theoretical acceleration, at, for each case. In both cases the force applied is a gravitational force; the weight (mhg) of the hanging mass. The mass of the system for each of the two cases is the mass. of the glider plus the mass of the hanging weight plus any mass taped to the glider. 10. For each case, determine tavg, the average of t1, t2, t3, to be used as "t" in Eq. (3) to find Vr, the final velocity. 11. Use the value of vr from the previous step in Eq. (2) to calculate the experimental acceleration of the system ag. Recall that the initial velocity Vo is equal to zero because the masses were released from rest. 12. For each of the two cases, calculate the percent error of your experimentally determined acceleration, aE, using Eq. (4).