Kinematics 2D ~ Lab. Part 1: Type 1 Projectile Launch. BCLN PHYSICS - Rev. Sept/2011

Transcription

1 Kinematics 2D ~ Lab Name: Instructions: Using a pencil, answer the following questions. The lab is marked based on clarity of responses, completeness, neatness, and accuracy. Do your best! Part 1: Type 1 Projectile Launch In this section, you will be using the Lab Resources > Video: Type 1 Projectile 1. How long did it take the projectile to return to the ground once it was shot? 2. Using kinematic equations and showing all your work please calculate the speed at which the projectile was shot from the gun. Show your work, as laid out in example problems. 3. What is the expected time in the air for the projectile shot horizontally? Show your work, as laid out in example problems. 4. What is the expected horizontal range of the projectile? Show your work, as laid out in example problems. Page 1 of 7

2 Part 2: Type 2 Projectile Launch In this section, you will be using the Lab Resources > Video: Type 2 Projectile 1. Using the vertical launch data provided in the video, determine the launch speed of this cannon. 2. Calculate the expected horizontal range of the projectile as it returns to the ground for the 45 degree launch. 3. Are your calculated values for the range likely to be larger or smaller than the experimental value? Provide two sources of error that that would explain your decision. Page 2 of 7

3 Part 3: Projectile Launch In this section, you will be using the Lab Resources > Media: Projectile Launch At the top right click tank shell, then set the angle to 60 and the speed to 16m/s. Leave the mass and diameter as they are. 1. Calculate the expected time the projectile will spend in the air, assuming it behaves as a Type 2 projectile. 2. Calculate the maximum expected height for this projectile. 3. Calculated the expected horizontal range for this projectile. Set the measuring tape at the origin and measure out the distance for your range. Place the bull s-eye here so it is even with the x axis. Fire the projectile. If you miss the bull s-eye, check your work, erase the current trajectory, and fire again. 4. What does height at the top of the screen read? h = 5. What does this mean? (discuss exactly what this number represents - magnitude and direction)? Page 3 of 7

4 6. Take the measuring tape and determine the actual range (where the projectile hits the ground as opposed to where it crosses the x-axis. Note the actual time. Why were your answers to part 1 close, but not exact? 7. Calculate the time necessary for the projectile to fall 1.2 m below the height from which it was fired. Show your work and be wary of negative signs. You will ultimately have to use the quadratic equation: 8. The quadratic equation will help you solve for two times. Why does only one make sense? 9. Is the time calculated in #7 bigger or smaller than the time calculated in #1? Explain. Without erasing this trajectory, find another angle that yields the same range as 60 degrees (at the point where it crosses the x-axis). 10. Find two more pairs of angles that yield the same range for type 2 projectiles: Pair 1 Range Angle 1 Angle 2 Pair Two different projectiles are launched at 16 m/s from two different angles; 70 and 20. Page 4 of 7

5 a) Determine the velocity components (vert and hor) of the 70 projectile. b) Determine the velocity components (vert and hor) of the 20 projectile. c) Which has the greater height? Why? (refer to components) d) Which is in the air longer? Why? e) Explain why the projectiles have the same range. 12. What can we say about two angles that share the same range (describe any symmetry with respect to 45 degrees)? 13. Which angle will always give the maximum range? Why? (Check through the simulation that this angle has the greatest range) 14. What would be the range of a projectile shot straight up in the air?. Page 5 of 7

6 Check air resistance, and then click through all of the other objects at the top. 15. Which objects have the greatest drag coefficient? 16. What is your guess as to why these objects are the greatest? 17. One day after school you are enjoying a can of soda. After it s empty you decide to toss it in the trash can. What variables determine whether or not you make the shot? 18. Design a Test: You ve heard the claim that a bullet shot horizontally will strike the ground at the same time as a bullet dropped from the same height. Use the PhET simulation to test this theory. a) Describe IN DETAIL what you did to the variables on the simulation to test the theory: b) Record your findings (time of flight, distances, angles, etc): c) Did you prove or disprove the claim? d) Name at least two things that surprised you about projectile motion after performing the test. Page 6 of 7

7 19. Draw a picture of a typical path of a type 3 projectile (off of a cliff at an angle upwards). Use the phet sim to assist you. Label all the key terms, including any necessary explanations. 20. Fire the projectile above at 45 degrees. Keep this path on the screen. For this type 3 launch, determine the angle necessary to achieve maximum range. Why is it not 45 degrees as it is for type 2 projectiles. Conclusion: Summarize, in a brief paragraph, what relationships you have learned from this experiment. Be sure to include supporting evidence for your conclusions. Be sure to explain how acceleration is represented in both d-t and v-t graphs! Page 7 of 7