Lab 10

Lab 10: Energy and Work Laboratory Report Name: Allison Bischoff Lab Partner(s): Chloe Kidd Frances Ang Purpose of Experiment The purpose of this lab was to observe the relationships between different forms of energy, to test the relationships between different forms of energy, and to comprehend the physics definition of work. The first part of the experiment involved finding the final velocity using a rolling cart and a track at an angle. The rolling cart was tested 10 times, adjusting the angle of the track each time and measuring its height. Using the mass of the cart and the height of the track, the gravitational potential energy was found to then find the calculated final velocity so the calculated and actual velocity values could be compared. The second part of the experiment also involved measuring the final velocity but using a falling ball. This time the height from where the ball was dropped changed each trial, and the same components were used to calculate the final velocity to compare it to the actual. After all the necessary data was found, graphical analysis was used. Data & Analysis Data Table 10.1 Trial θ m (kg) Δ y (m) PE g (J) Calculated v f (m/s) Actual v f (m/s) % Diff. 1 7° .29741 .153 0.45 1.73 1.142 40.9% 2 9° .201 0.59 1.99 1.553 24.6% 3 11° .223 0.65 2.09 1.661 22.8% 4 13° .244 0.71 2.18 1.683 25.7% 5 15° .280 0.82 2.34 1.874 22.1% 6 17° .296 0.86 2.40 1.993 18.5% 7 19° .387 1.13 2.75 2.304 17.6% 8 21° .413 1.20 2.84 2.399 16.8% 9 23° .475 1.39 3.05 2.635 14.5% 10 25° .500 1.46 3.13 2.711 14.3% Data Analysis Question: Most of the final velocities were pretty close to each other. The percent error could be due to friction not being considered.

Lab 10: Energy and Work Laboratory Report Data Table 10.2 Trial m (kg) Δ y (m) PE g (J) Calculated v f (m/s) Actual v f (m/s) % Diff. 1 0.055 0.15 m .081 1.71 1.341 24.1% 2 0.20 m .108 1.98 1.620 20.0% 3 0.25 m .135 2.21 1.640 29.6% 4 0.30 m .162 2.42 1.975 20.2% 5 0.35 m .189 2.62 2.415 8.1% 6 0.40 m .216 2.80 2.664 4.9% 7 0.45 m .243 2.97 2.787 6.3% 8 0.50 m .270 3.13 2.932 6.5% Data Analysis Question: The percent error was minimal for the final velocities, which could be due to error in measuring the final velocity of the ball (the sensor detecting hand movement). Data Table 10.3 Object Trial Calculated W (J) Actual W (J) % Diff. Cart 1 0.446 0.194 78.7% 2 0.586 0.359 48.0% 3 0.651 0.410 45.4% 4 0.712 0.421 51.3% 5 0.817 0.522 44.1% 6 0.864 0.591 37.5% 7 1.129 0.789 35.4% 8 1.205 0.856 33.8% 9 1.386 1.032 29.2% 10 1.459 1.093 28.6%

Lab 10: Energy and Work Laboratory Report Post-lab Questions 1. Which has more potential energy — a 12 kg object on the earth or a 12 kg object on the moon? Explain and support your answer. The earth because it has a greater force of gravity 2. Can an object have both kinetic energy and gravitational potential energy? Explain your answer. Yes, because an object can be elevated above the ground and be moving at the same time 3. What factors could have contributed to having a different measured final velocity than predicted final velocity? Friction was not considered in the predicted final velocity, and although the final velocity was measured in a frictionless environment, there will still be some friction 4. If a 15 kg object falls from 10 m to the ground and then bounces 9 m off the ground, how much work in total has been done? 147 J

Lab 10: Energy and Work Laboratory Report 5. If dropped from the same height, which would have more kinetic energy, the ball or the cart? Explain and support your answer with data. Since kinetic energy is dependent on mass, the cart would have more kinetic energy because it has more mass. Error Analysis The first source of error is the assumption that there is no friction involved. Because this experiment takes place in a conservative environment, a frictionless system is supposed to be assumed. However, there is still some friction, and therefore, still some energy lost due to friction. Because friction is not accounted for in this lab, it could be the source of some of the percent error in the values. The second source of error occurred during the rolling cart setup. The angle of the track had to be adjusted to a new angle for each trial, however, the angle was based on human observation, which leads to observer bias. The percent error for the majority of the values was less than 20%, and this error could have contributed to it. Error 3: motion detector detected hand movement The third source of error occurred during the measurement of final velocity using a falling ball. The velocity of the falling ball was measured using a motion detector, but the ball had to be dropped using your hand. The purpose of this experiment was to detect the motion of the ball; however, the sensor also picked up on the movement of the hand. Although the percent error for the velocity values were pretty low, the detection of hand movement could have contributed to the percent error. Conclusions Write a fully developed paragraph . State whether your execution of the procedures was a success or failure based upon your purpose section. Support your conclusion(s) by providing relationships, trends, or specific numerical examples from your data. My conclusion from this lab was this it was a success. I expected to observe the relationships between different forms of energy, to test the relationships between different forms of energy, and to comprehend the physics definition of work. The percent error was mostly less than 25% for the velocity values; however, some of the work values had a higher percent error. Despite the percent error for some of the values, the graphical analysis of the data accurately demonstrated the relationships between the different forms of energy, and for these reasons, I would consider this lab to be a success.