lab 6_report

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Century College *

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1020

Subject

Mechanical Engineering

Date

Dec 6, 2023

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docx

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Part I. 1. Use the Energy Graphs to track the Skater's mechanical energy. Decide which graphs or charts best help you understand what makes your track successful. 2. Explain why your track is successful in terms of conservation of mechanical energy. Refer to Charts or Graphs to help explain your reasoning. 3. Using conservation of mechanical energy, explain what things need to be considered when designing any successful track. The pie chart helps me better track the mechanical energy of the skater. If the entire chart is 100% of the skater’s energy, it is easier to understand the conservation of the energy and how it is converted from one form to another at different points of the track. The track is successful if the total mechanical energy is conserved. That means the skater's total mechanical energy remains constant throughout the entire track, or the energy is being conserved. The skater's potential energy is converted into kinetic energy in the lack of friction (or disordered energy). The pie chart shows how potential energy starting at the top of the track is gradually converted into kinetic energy when the skater moves down with increasing speed, and the kinetic energy is converted back to the potential energy as the skater moves up from the lowest point. Several things should be considered when a successful track is designed to ensure the total mechanical energy is conserved. In this case, the equation TME =  PE +  KE – W f is functional. The track should be designed to minimize friction as work done by friction reduces the skater’s mechanical energy, or friction converts the skater’s mechanical energy into thermal energy/heat. The change from the gained potential energy to kinetic energy is essential for the skater to get enough mechanical energy to skate over the track without stopping or failing. Each variable of potential energy, PE = mgh, and kinetic energy, KE=1/2mv 2 , should be considered. The skater’s mass can affect PE and KE as it is directly proportional to. Additionally, the track height should be designed to regulate the skater’s speed, ensuring a skater doesn’t gain too much or too low speed. (For instance, the more mass, the more PE is possessed on the top of the track that is transferred into KE, which impacts the speed, but the friction increases simultaneously.)

Inna Van Amber 10/29/2023 4. By adding friction, explain what changes in the simulation when you add friction. How does the energy distribution change? Part II. 1. Paste your position versus time graphs. When friction is added, there are changes in the energy chart where thermal energy appears, and the skater’s speed decreases. Friction converts some skater’s mechanical energy into thermal energy, which is disordered, meaning that the skater’s total mechanical energy is not conserved. In other words, friction converts the skater’s kinetic energy to thermal energy; as a result, the skater’s speed decreases over time/distance, and the skater's ability to go up or gain potential energy decreases, or the ability to complete the track differs on value of friction. Thermal energy increases with the distance covered by the skated. 0 0.5 1 1.5 2 2.5 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 Super ball y (m) vs time (s) Time (s) Y (m) 0 0.5 1 1.5 2 2.5 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 Super ball y (m) vs time (s) Time (s) Y (m)

2. Determine the coefficient of restitution for the super ball and the golf ball. Describe your procedure. 3. What value did you obtain for the coefficient of restitution of the super ball? 4. What value did you obtain for the coefficient of restitution of the golf ball? The ratios h 2 /h 1 and h 3 /h 2 are the coefficients of restitution of each bounce of the super ball and golf ball. Where h 1 , h 2 , h 3 the maximum height reached after each bounce. I defined the ratios of three maximum heights after three bounces for the super ball and the golf ball to compare. Highest points values: h 1 = 1 m; h 2 = 0.9341 m; h 3 = 0.8736 m. Coefficients of restitutions after bounce 1, 2, 3: e 1,2 = h 2 / h 1 = 0.9341 m e 2,3 = h 3 / h 2 = 0.9352 m Average coefficient of restitution for the super ball: e avg = 0.9347 Highest points values: h 1 = 0.9167 m; h 2 = 0.7722 m; h 3 = 0.65 m. Coefficients of restitutions after bounce 1, 2, 3: e 1,2 = h 2 / h 1 = 0.8424 m e 2,3 = h 3 / h 2 = 0.8418 m Average coefficient of restitution for the golf ball: e avg = 0.8421

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Inna Van Amber 10/29/2023 5. What is the significance of these values? What does the coefficient of restitution tell you about energy? 6. Which ball is the "livelier" ball? Let's compare the coefficients of the restitution of the super ball, e avg = 0.9347, and the golf ball, e avg = 0.8421. We see that the super ball's coefficient has the higher value, which means that the super ball's material has higher elasticity and strength in the collision with the floor. Also, the coefficient of restitution can be found as a ratio of speeds (just after a bounce to just before a bounce) or v 2 2 /v 1 2 = h 2 /h 1 Speed squared is directly proportional to kinetic energy, we can determine the ratio of outgoing kinetic energy (just after bounce) and incoming kinetic energy (just before bounce) or KE out /KE in = v 2 2 /v 1 2 n other words, we can compare how much of the ball's kinetic energy remains after bounce/collision with the floor. Since both coefficients of the restitution are less than 1.0 as KE in < KE out , it means some kinetic energy is converted into thermal energy due to deformation in the collision. However, thermal energy is disordered energy, which means some amount of mechanical energy is lost. The closer the value of the coefficient of the restitution is to 1.0, the lesser kinetic energy loss, meaning that with a higher coefficient of restitution, a ball rebounds higher. In our experiment, the super ball lost less energy: 0.8421< 0.9347<1.0. The livelier ball means the ball can rebound many times close to an initial high and velocity for a longer time, or a ball’s material stores the mechanical energy efficiently and loses less kinetic energy after each bounce.