Experiment: Go-Kart Challenge

Transcription

1 Experiment: Go-Kart Challenge Research Question Does mass affect the acceleration of a rider? Hypothesis I predict that as we increase the mass of a rider the acceleration of the rider will (increase, decrease, remain the same). Explain your hypothesis. Why do you believe the acceleration will increase, decrease, or remain the same? Procedure 1. Predict which student in your class will have the greatest acceleration. Provide an explanation justify your reasoning. 2. Mark off 10 meter intervals for a total distance of 50 m. 3. Place a timer at each of the ten meter intervals. 4. how long it takes a heavy, a medium, a light rider to reach each point from the beginning. 5. Complete the analysis questions. 6. Plot a graph of 2d vs. t 2 for the light rider, medium heavy rider. 7. Highlight your 2d vs. t 2 data then select Insert then choose Scatter select the 1 st subtype as shown below. 8. Under Chart Tools click on Layout. Click on Chart Title label the graph as Distance vs.. Click on Axis Titles label the x y-axes appropriately. Click on Legend then click on None. Click on Gridlines make sure Major Gridlines are selected for both axes. Finally, right click on a data point in your graph select Add Trendline. Place a check mark in the bottom two boxes: Display equation on chart Display R 2 value on chart. Remember that the R 2 value represents the correlation coefficient indicates how closely your data falls on the displayed trendline.

2 Heavy Rider 0 m 10 m 20 m 30 m 40 m 50 m Trial 1 Trial 2 Trial 3 Average Medium Rider 0 m 10 m 20 m 30 m 40 m 50 m Trial 1 Trial 2 Trial 3 Average Light Rider 0 m 10 m 20 m 30 m 40 m 50 m Trial 1 Trial 2 Trial 3 Average

3 Analysis 1. Fill out the table below from the class calculations. Light Rider t 2 (seconds 2 ) 2d (meters) Acceleration (m/s 2 ) Medium Rider t 2 (seconds 2 ) 2d (meters) Acceleration (m/s 2 ) Heavy Rider t 2 (seconds 2 ) 2d (meters) Acceleration (m/s 2 ) Conclusion 1. A constant slope (straight-line) would give a constant acceleration. Does your data support or not support this? What does the data indicate about the acceleration of the light, medium heavy riders? 2. What conclusion can you make about the relationship between mass (light, medium, heavy) acceleration? Cite several examples from your data table to support your answer. 3. Describe how each of the following could be a source of error in this lab how each source would affect the results of the collected data: Friction Measurement of displacement Measurement of time

4 Rubric Go-Kart Challenge Honors Physics Heading (1 pt.) Research Question (2 pts.) Hypothesis (5 points) Sketch & Description (5 pts.) Data Tables & Graph (25 pts.) Conclusion (10 pts.) Bonus (2 pts.) Total = /50 points Student labels the date in the upper left h corner title of lab in all CAPS in lab notebook. Student states the research question of the lab as a statement. Student states hypothesis explains their prediction. Student sketches materials used in lab a brief description of what they did. Student uses a ruler to create a data table of distance, time speed with the correct labels calculations for each measurement. Student plots a x-y scatter graph of 2d vs. t 2 using Microsoft Excel, labels axes with units, displays R 2 value trendline. Student proves if mass affects the acceleration of a rider by citing data collected in the data table AND graph. Student completely explains how each source of error would affect their results. Student discusses the findings of Galileo s leaning tower of pisa experiment includes a sketch of the experiment.

5 Option 1: Performance Assessment Honors Physics What understings or goals would be assessed through this task? Students will identify the forces acting on a self-propelled vehicle explain how the motion of the vehicle demonstrates Newton s laws. Through what authentic performance task will students demonstrate understing? Task overview: You will design, build, test a self-propelling vehicle that can travel a minimum distance of one meter. When designing the vehicle, sketch a diagram showing how it will be propelled (balloon, rubber b, mousetrap, etc.) the forces that act on the vehicle when it is stationary moving. After building testing the vehicle, write an essay explaining how your vehicle demonstrates Newton s three laws of motion. What student products performances will provide evidence of desired understings? Self-propelling vehicle prototype Vehicle schematic showing propulsion mechanism forces acting on vehicle Essay detailing how the vehicle demonstrates each of Newton s laws

6 PERFORMANCE ASSESSMENT: NEWTONIAN VEHICLE PERFORMANCE LEVELS CRITERIA FOR SUCCESS Isaac Newton Ranked Pretty Decent Better keep the pads Crash Burn Vehicle Constructed Vehicle is selfpropelled moves 1-meter Vehicle is selfpropelled moves less than 0.75 meters. Vehicle is selfpropelled moves less than 0.50 meters. Vehicle is selfpropelled moves less than 0.25 meters. Vehicle does not move. Accuracy of Scientific Terms No mistakes 1 mistake 2 mistakes 3 mistakes 4 mistakes Newton s 1 st Law Fully Partially incorrect or not incorrect not missing Newton s 2 nd Law Fully Partially incorrect or not incorrect not missing Newton s 3 rd Law Fully Partially incorrect or not incorrect not missing

7 Option 2: You are a skateboarder who has been asked to compete at the state x-games by your skater buddies will be wowing the world with your fearless feats. When you take the x-games cup, your buddies want explanations for your gravity defying performance. Write an describing the stunts used during your competition. Explain how you used Newton s laws of motion to ace each stunt. Include five stunts identifying at least one Law per stunt. All three laws must be used. PERFORMANCE ASSESSMENT: EXTREME GAMES PERFORMANCE LEVELS CRITERIA FOR SUCCESS Number of Stunts Explained Accuracy of Scientific Terms 5 Tony Hawk 5 fully 4 Ranked 4 fully 3 Pretty Decent 3 fully 2 Better keep the pads 2 fully 1 Crash Burn 1 fully No mistakes 1 mistake 2 mistakes 3 mistakes 4 mistakes Newton s 1 st Law Newton s 2 nd Law Newton s 3 rd Law Fully Fully Fully Partially Partially Partially incorrect or not relevant to incorrect or not relevant to incorrect or not relevant to incorrect not incorrect not incorrect not missing missing missing

8 The Coefficient of Friction Honors Physics Theory When an object is in motion along a rough surface, the force of friction acts opposite to the direction of the object s motion. The coefficient of friction depends on: a) the force between the two surfaces, b) the roughness of the two sliding surfaces. Materials spring scale wooden block set of masses s paper mirror Procedure 1. Use the spring scale to measure the weight of the wooden block. Make sure you measure the weight in Newtons. Record the Weight of Block for all four trials in Data Table1. 2. You will be adding weight to the top of the block. Weights such as 1 N, 2N, 3 N, etc. work well. Choose some additional weight place it on the block. Record this under Added Weight in Data Table Add the weight of the block the added weight. Record this under Total Weight in Data Table You will be pulling your block along a horizontal surface, so the total weight (mg) will be equal to the normal force. Copy the total weight value to the F Normal value in Data Table Place the wooden block on your lab table. Using the spring scale pull it at a constant rate. Measure the applied force (read it off the spring scale in Newtons). Record this under F app = F friction in Data Table You now have all your information for Trial 1. Repeat steps 2 5 using different added weights each time. 7. Choose a different surface repeat steps 2 6. Put your values in Data Table 2. Be sure to record what your surfaces are! 8. Choose a final surface in the lab room (its up to you!). Complete the third data table.

9 Data Table 1 Surface: Trial Weight of Block (N) Added Weight (N) Total Weight (N) F Normal F app =F friction μ k Table 2 Surface: Trial Weight of Block (N) Added Weight (N) Total Weight (N) F Normal F app =F friction μ k Table 3 Surface: Trial Weight of Block (N) Added Weight (N) Total Weight (N) F Normal F app =F friction μ k

10 Analysis 1. Sketch the setup of the experiment. 2. Label the free body diagram 3. Solve for μ k in the equation F fr = μ k F N Algebraic Approach 4. Using your equation for μ k from step 3, fill in the last column in the data tables. 5. Calculate the average μ k for each surface a) Surface 1: b) Surface 2: c) Surface 3: Graphical Approach 6. Graph F friction vs. F Normal for the 3 different surfaces on the same graph. Connect the points for the same surface with a STRAIGHT LINE. You will have 3 separate lines. (F Normal on x-axis, F friction on y-axis) 7. You can use the slope of your graph to find the coefficient of friction for the different surfaces. Find μ k for the 3 surfaces. a) Surface 1: b) Surface 2: c) Surface 3: Conclusions 1. Record the coefficients of friction using the different approaches. Surface μ k using algebraic approach μ k using graphical approach 2. Which surface had the smallest coefficient of friction between the two surfaces?

11 3. Which surface had the largest coefficient of friction between the two surfaces? 4. How did the coefficient of friction relate to the types of surface you used? 5. What happened to the friction when you increased the weight on the block? 6. What happened to the coefficient of friction when you increased the weight on the block? 7. Propose several (at least 3) ways to reduce the amount of friction. 8. List two sources of error in this experiment explain in detail how these sources of error would affect the results of your experiment.

12 Rubric Coefficient of Friction Honors Physics Mechanics (2 pts.) Research Question (2 pts.) Sketch & Description (5 pts.) Data Tables & Graph (25 pts.) Conclusion (16 pts.) Total = /50 points Student makes no grammatical errors in the lab report. Student states the research question of the lab as a statement. Student sketches materials used in lab a brief description of what they did. Student uses Microsoft Excel or similar program to create data tables. Student plots a x-y scatter graph of F friction vs. F normal using Microsoft Excel, labels axes with units, displays R 2 value trendline. Student answers questions in complete sentences references data tables evidence to support each conclusion. Student completely explains how each source of error would affect their results.