What is Projectile Motion?

1. What is Projectile Motion?

2. Instructional Objectives: • Students will be able to: • Define Projectile Motion • Distinguish between the different types of projectile motion • Apply the concept to flying marble and measure its velocity • TEKS 5.A and 5.B

3. Projectile Motion • Two-dimensional motion of an object • Vertical • Horizontal

4. Types of Projectile Motion • Horizontal • Motion of a ball rolling freely along a level surface • Horizontal velocity is ALWAYS constant • Vertical • Motion of a freely falling object • Force due to gravity • Vertical component of velocity changes with time • Parabolic • Path traced by an object accelerating only in the vertical direction while moving at constant horizontal velocity

5. Examples of Projectile Motion • Launching a Cannon ball

7. Variables

8. Equations • X- Component • Y- Component • Vectors Note: g = 9.8 m/s2 (Acceleration due to gravity)

9. Factors Affecting Projectile Motion • What two factors would affect projectile motion? • Initial velocity • Angle Initial Velocity Angle

10. Solving Problems Involving Projectile Motion • Read the problem carefully, and choose the object(s) you are going to analyze. • Draw a diagram. • Choose an origin and a coordinate system. • Decide on the time interval; this is the same in both directions, and includes only the time the object is moving with constant acceleration g. • Examine the x and y motions separately.

11. Solving Problems Involving Projectile Motion 6. List known and unknown quantities. Remember that vx never changes, and that vy = 0 at the highest point. 7. Plan how you will proceed. Use the appropriate equations; you may have to combine some of them.

12. Group Practice • Interactive projectile motion calculator http://library.thinkquest.org/10796/ch6/ch6.htm • Other explanations and practice problems http://tuhsphysics.ttsd.k12.or.us/Tutorial/Lessons/Projectile.htm#GenStrat

13. Class Exercise An object is fired from the ground at 100 meters per second at an angle of 30 degrees with the horizontal • Calculate the horizontal and vertical components of the initial velocity • After 2.0 seconds, how far has the object traveled in the horizontal direction? • How high is the object at this point?

14. Solution • Part a • Part b • Part c

15. Additional Group Exercises • See handouts, other presentations, or textbook examples

16. Applications Any Ideas?

17. Summary of Concepts • A projectile is any object upon which the only force is gravity, • For our purposes we will not consideration air resistance, so we will take the approach all bodies fall at the same rate regardless of their mass • Projectiles travel with a parabolic trajectory due to the influence of gravity, • There are no horizontal forces acting upon projectiles and thus no horizontal acceleration, • The horizontal velocity of a projectile is constant (a never changing in value), • There is a vertical acceleration caused by gravity; its value is 9.8 m/s/s, down, • The vertical velocity of a projectile changes by 9.8 m/s each second, • The horizontal motion of a projectile is independent of its vertical motion.

18. Independent Practice – problem sets Set 1 Set 2 Set 3

19. Labs • CPO Manual B-1: Launch Angle vs. Range B-2: Launch Angle vs. Speed B-3: Analysis of Range and Speed

20. Acknowledgements • gk12.poly.edu/.../RAISE...PowerPointFiles/Projectile%20Motion.ppt