Verification of Work Energy Theorem PDF

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Introduction, Materials, Procedure, Data (all lab parts) and question and answers...

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Physics 1441-D767 3 December 2018

Lab 8: Verification of Work-Energy Theorem Intro: In this lab, we will determine the coefficient of kinetic friction and verify the Work energy theorem. To start we need to know what goes into the work-energy theorem. We have two kinds of energy potential energy and kinetic energy. When added together they equal the total mechanical energy. Potential energy is the energy an item has based on its position. Kinetic energy is the energy of motion. We also have forces that come into play, conservative and nonconservative. Conservative forces can be gravitational forces or deal with springs. Nonconservative forces are external and when they are present we have the Work energy theorem. The work done by nonconservative forces is equal to the change in mechanical energy, this is known as the work-energy theorem.

Procedure: ● Measure the mass of the block and the length of the flag ● Set up photogates ● Place the block on an adjustable incline ● Tap the block and see if it moves ● When the block slides down after being taped at what seems to be a constant speed record the angle ● Measure the vertical distances ● Compute with different mass then compute with different masses and angles

Data:

Analysis: We see that as the mass increases the angle differs but the mesn value of the angle is always the same and so is the coefficient of Kinetic Friction. As our mass increases our angle didn't follow a pattern or either increasing or decreasing it was all over the place. When you look at how are mass increased from 0.25hgs to 0.4kgs the angle doesn't follow. Our angle started at 18 degrees, remained at 18degress and then increased to 19degreesbut then it went all the way back down to 15 degrees.

Analysis: Here we see that at an angle of 15 degrees and from masses 0.1kgs to 0.4kgs the initial velocity is always lower than the final velocity for example for 15 degrees at 0.1kgs the initial

velocity is 1.31m/s and the final velocity is 2.15 m/s. We have the same pattern for the rest of15 degrees. For the angle of 20 degrees we see the pattern but this time we see the final velocity become a lot higher than the initial velocity. As for energy we see that change in energy is the highest at the higher degree and heaviest weight and lowest at the lower angle and lower weight.

Conclusion: In this experiment, we used different angles and different masses to calculate the coefficient of kinetic friction which is µk = tan(θ) ours was .3175. The block sliding down the ramp has friction going in the opposite direction that the block slides down in. The heavier the weight of the block the more friction there is. As for the work-energy theorem, the change in energy is highest at the highest angle and weight and lowest ath the lowest and angle and weight this is because the external forces have to do more work for the block to slide down at a constant speed.

Questions: 1. When the block moves an incline plane, what kind of energy transformation takes place> Answer: the kind of energy transformation taking place is kinetic energy. 2. Distinguish between the static and kinetic friction. Explain why it is necessary for the block to move at a constant velocity to determine the coefficient of kinetic friction. Answer: Static friction matches applied force to prevent an object from moving, Kinetic friction has to overcome the max static friction to gain motion. 3. Step 8 of the procedure states that the block must be released from the same point for each trip. Why? Answer: The block must be released from the same point because if the velocity changes then the friction will also change. 4. Does your data confirm the expected relationship between the work done by the kinetic friction and the change in the mechanical energy of the block? State clearly what is expected and what your data indicates.

Answer: My data partially confirms the relationship between kinetic friction and the change in the mechanical energy. The results for change in energy were positive while the changes in mechanical energy were negative. 5. A 2kg block slides down on an inclined plane and reaches the bottom with speed 4m/s. How much work does the force of friction do if the block starts from rest at a height of 1.5m Answer: 13.4 J 6. A ball of mass 0.2 kg is thrown straight upward with an initial speed of 15 m/s. When the ball returns to the same level, its speed is 13 m/s. How much work does air resistance do on the ball during its flight? Answer: 5.6 7. A car is moving horizontally with a speed of 20m/s when it breaks to a stop. Where does all the kinetic energy of the moving car go? Answer: The kinetic energy is transformed into heat....