PHYS130 Collisions Lab - STUDENT VERSION-1

Siena College - General Physics 130 Collisions Lab NAME: Rebecah Leonard GROUP MEMBERS:Traevon, Jesse, Lilith Learning Goals 1. In Section I, you will investigate if any physical quantity (or quantities) remain the same both before and after a collision for a two-cart system. 2. In Section II, you will test the physical quantity that you’ve determined remains constant in Section I’s experiments to make a prediction of the ratio of Eugenia’s and Bor’s speeds ( v Eugenia / v Bor ) after Eugenia pushes Bor 3. In Section III, you will use your knowledge of impulse to explain the motion of the carts in the video and estimate the impulse and force that the air exerts on the carts. 4. In Section IV, you will estimate the change in the total mechanical energy of a 2-cart system and explain what other forms of energy it was converted into. In addition, you will also explain the mechanism that made one of the carts speed up after it momentarily came to rest. Section I - In this part of the lab, you will investigate if any physical quantity (or quantities) remain the same both before and after a collision for a two-cart system. Equipment: Graphical Analysis, dynamics track, 2 Vernier Go Direct carts, magnetic bumpers, velcro bumpers. Scientific Ability Missing Inadequate Needs Improvement Adequate G4 Is able to record and represent data in a meaningful way The data is either absent or incomprehensible. Some important data is absent or incomprehensible. The data is not organized in tables or the tables are not properly labeled. All important data is present, but it is recorded in a way that requires some effort to comprehend. The tables are labeled, but the labels are confusing. All important data is present, organized, and recorded clearly. The tables are labeled and placed in a logical order. B7 Is able to identify a pattern in the data No attempt is made to search for a pattern. The pattern described is irrelevant or inconsistent with the data. The pattern has minor errors or omissions. The pattern represents the relevant trend in the data. 1

Siena College - General Physics 130 Collisions Lab Set-up and run the following experiment with a two-cart system. A. Cart A, loaded with a 1 kg block, moves to the right at a gentle constant speed and hits a stationary and empty Cart B. Ensure that magnetic bumpers are attached to each of the carts. [ https://youtu.be/HbMBplGL3Zo ] Use the table that follows to help you investigate if any physical quantity (or quantities) remain the same both before and after a collision for a two-cart system. Physical quantities ⟶ Mass m kg Speed v m/s x- velocity component v x m/s Mass times speed Mv Kg*m/s Mass times x- velocity component mv x kg*m/s ½ times mass times speed squared (½)mv 2 Line 1: Cart A ( before collision) 1 .3 0.548 0.548 0.712 0.712 0.195 Line 2: Cart B ( before collision) 0.3 0 0 0 0 0 Combined physical quantity for Cart A & Cart B (add line 1 and line 2 for each quantity) 1.6 0.548 0.548 0.712 0.712 0. 195 Line 3: Cart A ( after collision) 1.3 0.499 0.499 0.584 0.584 0.131 Line 4: Cart B ( after collision) 0.3 0.433 0.433 0.13 0.13 0.028 Combined physical quantity for Cart A & Cart B (add line 3 and line 4 for 1.6 0.882 0.882 0.714 0.714 0.159 2

Siena College - General Physics 130 Collisions Lab Line 4: Cart B ( after collision) 0.3 0.026 0.015 0.005 0.061 0.000 Combined physical quantity for Cart A & Cart B (add line 3 and line 4 for each quantity) 0.6 0.041 0.041 0.012 0.012 0.000 Circle or highlight the combined physical quantity or quantities that remained the same both before and after the collision for the two-cart system. Set-up and run the following experiment with a two-cart system. C. Cart A, loaded with a 1 kg block, moves to the right at a gentle constant speed. An empty Cart B moves to the left at the same gentle constant speed as Cart A. The carts collide and stick together. Ensure that velcro is attached to each of the carts. [ https://youtu.be/tciBA4w4ZiU ] Use the table that follows to help you investigate if any physical quantity (or quantities) remain the same both before and after a collision for a two-cart system. Physical quantities ⟶ Mass M kg Speed V m/s x- velocity component v x Mass times speed mv Mass times x- velocity component mv x ½ times mass times speed squared (½)mv 2 Line 1: Cart A ( before collision) 1.3 0.265 0.265 0 .345 0.345 0.045 Line 2: Cart B ( before collision) 0.3 0.138 0.138 0.041 0.041 0.012 Combined physical quantity for Cart A & Cart 1.6 .403 .403 0.386 0.386 0.057 4

Siena College - General Physics 130 Collisions Lab B (add line 1 and line 2 for each quantity) Line 3: Cart A ( after collision) 1.3 0.249 0.249 0.324 0.324 0.040 Line 4: Cart B ( after collision) 0.3 0.249 0.249 0.075 0.075 0.009 Combined physical quantity for Cart A & Cart B (add line 3 and line 4 for each quantity) 1.6 0.498 0.498 0.399 0.399 0.049 Circle or highlight the combined physical quantity or quantities that remained the same both before and after the collision for the two-cart system. After you come up with a physical quantity that is the same before and after each collision, decide which quantities remain constant in ALL FOUR experiments. The momentum and kinetic energy are conserved before and after the collision and the mas remains the same for all experiments. Section II - In this part of the lab, you will test the physical quantity that you’ve determined remains constant in Section I’s experiments to make a prediction of the ratio of Eugenia’s and Bor’s speeds (v Eugenia / v Bor ) after Eugenia pushes Bor. Equipment: Video in part (c). Scientific Ability Missing Inadequate Needs Improvement Adequate A9 Mathematical No representation is constructed. The mathematical representation lacks the algebraic part (the student plugged in the numbers right away), has the wrong concepts being applied, signs are incorrect, or progression is unclear. No error is found in the reasoning. However, there may not be fully completed steps to solve the problem or one needs considerable effort to comprehend the progression. No evaluation of the math in the problem The mathematical representation contains no errors and it is easy to see the progression from the first step to the last step in solving the equation. The solver evaluated the mathematical representation. 5

Siena College - General Physics 130 Collisions Lab your prediction for the ratio of the two speeds. What can you say about your confidence in the new physical quantity that you used to make the prediction? The experimental measurement agrees with your prediction for the ratio of the two speeds because it’s in the range of my prediction. The experimental measurement for the ratio of the two speeds is .64 which is about 20% of my prediction. The deviation in the number can be due to energy lost to friction and the environment. Section III - In this part of the lab, you will use your knowledge of impulse to explain the motion of the carts in the video and estimate the impulse and force that the air exerts on the carts. Equipment: Videos in parts (a) and (b). Scientific Ability Missing Inadequate Needs Improvement Adequate A11 Graph No graph is present. A graph is present, but the axes are not labeled. There is no scale on the axes. The data points are incorrectly connected to each other instead of using an appropriate trendline. The graph is present and the axes are labeled, but the axes do not correspond to the independent and dependent variable OR the scale is not accurate. The data points are not connected to each other, but there is no trendline either. The graph has correctly labeled axes, the independent variable is along the horizontal axis and the scale is accurate. The trendline is correct. A9 Mathematical No representation is constructed. The mathematical representation lacks the algebraic part (the student plugged in the numbers right away), has the wrong concepts being applied, signs are incorrect, or progression is unclear. No error is found in the reasoning. However, there may not be fully completed steps to solve the problem or one needs considerable effort to comprehend the progression. No evaluation of the math in the problem is present. The mathematical representation contains no errors and it is easy to see the progression from the first step to the last step in solving the equation. The solver evaluated the mathematical representation. A. Use your knowledge of impulse (Net Impulse = F Environment on System Δt = mv f - mv 0 ) to explain the motion of the carts in the video below (specifically, identify the object that exerts the impulse on the carts) and to predict the shape of the velocity-vs-time graphs in the following experiments: [ https://youtu.be/LEHPPXRwLX4 ]. The object that exerts the impulse on the cart is the fan attached to the back of it. The 7

Siena College - General Physics 130 Collisions Lab motion of the cart begins by increasing at constant acceleration once the fan is turned on. After the fan is turned off the cart will stop increasing its velocity and start traveling at a constant speed. The shape of the velocity-vs-time graph will look like a ramp that increases at a constant rate initially then flattens out or plateaus. B. Watch the following video [ https://youtu.be/AB2F3yukAkE ] to compare your prediction to the outcome. Discuss the differences if any occurred. The prediction I gave is consistent to the outcome. C. Use the graphs and other data from the video above to estimate the impulse and force that the air exerts on the carts. Check if this force is the same in all experiments. Should this force be the same or different? How do you know? The force that the air exerts on the carts is 40N. The impulse the air exerts on the cart in experiment 1 is 40J. The impulse the air exerts on the cart in experiment 2 is 80J. The impulse the air exerts on the cart in experiment 3 is 120J. The force should be the same since the carts accelerate constantly and the mass of the carts remains the same. The impulse the carts experience in each experiment is different because the force is applied for different amounts of time. Section IV - In this part of the lab, you will estimate the change in the total mechanical energy of a 2-cart system and explain what other forms of energy it was converted into. In addition, you will also explain the mechanism that made one of the carts speed up after it momentarily came to rest. Equipment: Video. Scientific Ability Missing Inadequate Needs Improvement Adequate B9 Is able to devise an explanation for an observed pattern No attempt is made to explain the observed pattern. An explanation is vague, not testable, or contradicts the pattern. An explanation contradicts previous knowledge or the reasoning is flawed. A reasonable explanation is made. It is testable and it explains the observed pattern. 8

Siena College - General Physics 130 Collisions Lab system is constant in this process? If not, explain what might have caused the total momentum change. Can you say that the total mechanical energy of the system is constant in this process? If not, estimate the change of the total mechanical energy and explain into what other forms of energy it was converted. We can say that the total momentum of the system is constant in this process. The initial momentum of the system was .35595 kg*m/s and the final momentum was .34465 kg*m/s. These numbers are very close to each other and allow us to say that momentum was conserved in the collision. The slight loss of momentum can be explained by the spring on Cart A which took energy to compress and shoot Car B back. B. At t = 0.35 s, cart A almost stopped moving but after that time it sped up and continued moving with constant speed. Explain the mechanism that made cart A speed up again. (Hint: watch the video and carefully observe cart A during the collision.) The mechanism that made cart A speed up again was the spring attached to Cart A. There was energy stored in the spring from being compressed during the collision between Cart A and B. The spring hit Car B and made Cart A experience an equal and opposite force from the spring being decompressed and releasing that stored energy causing it to speed up again . 10