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TWO DIMENSIONAL MOTION

TWO DIMENSIONAL MOTION. Pre-Class Thursday 2-2-12 What is the name of the path followed by a projectile--something launched, hit, kicked into the air? Hint: think back to math class. Begin chapter 6: Motion in Two Dimensions. Terminal Velocity.

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TWO DIMENSIONAL MOTION

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  1. TWO DIMENSIONAL MOTION Pre-Class Thursday 2-2-12 • What is the name of the path followed by a projectile--something launched, hit, kicked into the air? Hint: think back to math class. • Begin chapter 6: Motion in Two Dimensions

  2. Terminal Velocity • The maximum speed that can be obtained by a falling object • The force of gravity is equally balanced by the air resistance force (drag) • Constant speed, no acceleration Let's try an activity...

  3. Materials Meter stick Paper Stopwatch Scissors Procedures Drop a flat piece of paper 2 m. Measure the time for it to fall. Crumple the piece of paper into a loose ball. Measure time to fall in 2 m. Crumple the piece of paper into a tighter ball. Measure time to fall 2 m. Use the scissors to design your own paper object. Measure time to fall 2 m. Measuring Effects of Air Resistance What characteristic of the paper affected the falling time the most?

  4. What is a projectile? Any object shot through the air How does it travel? Follows a parabolic path Let’s look at one EQUATIONS OF MOTION will change…slightly PROJECTILE MOTION

  5. NEW EQUATIONS OF MOTION Y direction vf = (vi sinq) - g t y = (vi sinq) t - 1/2 g t2 vf2 = (vi sinq)2 - 2 g y X direction vf = vi x = vi (cosq) t

  6. Range Equation • If a projectile launches and lands from the same vertical height, we can find the distance traveled in the x by the following: R = vi2 (sin 2q)/g • Notice the angle is doubled and the initial velocity is squared • The unit for range is meters (m)

  7. Pre-class for Friday 2-3-12 A boy standing on a balcony drops one ball and throws another with an initial horizontal velocity of 3 m/s. Which of the following statements about the horizontal and vertical motions of the balls is correct? (Neglect air resistance.) • The balls fall with a constant vertical velocity and a constant horizontal acceleration. • The balls fall with a constant vertical velocity as well as a constant horizontal velocity. • The balls fall with a constant vertical acceleration and a constant horizontal velocity. • The balls fall with a constant vertical acceleration and an increasing horizontal velocity.

  8. Centripetal Acceleration • The acceleration on an object to keep it traveling in a circular path • The direction is always pointed towards the center, perpendicular to the velocity ac=v2/r

  9. Centripetal Force • Force required to keep an object traveling in circular motion Fc = mac = mv2/r • This is different than the “fictional” force of centrifugal force…which does not exist.

  10. Materials String/block Stopwatch Meter stick Spring scale Procedures Measure m, r, and T of the slowly, spinning block Calculate v, ac, and Fc. Repeat using 2 different radii. CENTRIPETAL LAB

  11. Pre-class Monday 2-6-12 Neglecting air resistance, the initial horizontal velocity of a projectile is _____ its final horizontal velocity. a. Greater than • Less than • Equal to • Not related to

  12. Ch6 Homework 51. 28.9 m 53. 3.2 m 56. 31 m, 212 m 58. 14.3 s, 497 m 60. 11.8 m/s 61. 9.65 m/s2; 5937 N 62. 71 m/s2, 500 N 65. 18 m/s 67. 1,470 m 70. 5m/s, 53o, 3m/s //, 4m/s ┻

  13. Objective: find the place where the ball will hit Materials: golf ball measuring tape stop watch masking tape PROJECTILE LAB

  14. Find the time for the ball to fall from the table Find the velocity of the golf ball as it leaves the table Predict where the ball will land repeat two more times for accuracy PROCEDURES

  15. TO TURN IN (show your work) • Was your prediction correct? • If not, why? • What was the initial velocity in the y direction?

  16. PERIODIC MOTION PERIODIC • Take attendance • go over homework problems • What is periodic motion? • Centripetal force is a “fictional” force • pendulums(equation) • circular motion

  17. PENDULUMLAB • Each group needs: • pendulum • stop watch • meter stick • measure the difference in T for 5 different lengths of string • use 10,20,30,40,50 cm • lengths

  18. Pre-Class for Friday 8-31-07 Write: “Egg Drop Project”for today’s pre-class When completed, put in proper basket in the back. Be sure your name is on it!

  19. Egg Drop Parachute Rules • Nothing added to egg to improve its strength • Raw, chicken eggs only • Less than 1 m from egg bottom to parachute top • Cannot be attached to anything on the ground or building (i.e. freefalling) • Must fit through the “fire escape” (the window) • Nothing attached to the egg to protect it…the egg must hit the ground first • One throw per group Due Monday

  20. Eggcellent ParachuteProject Procedures • Ensure the parachute is working properly…make any adjustments • Egg must be inspected before attaching to parachute (any cracks and/or rule violations) • Attach egg to parachute • Egg/parachute must be inspected again • Walk to N237 (Physics Lab) • 1 person from each group will stay in the lab to drop the egg/parachute • All other group members will be outside with me • After each drop, I will inspect the egg for damage Today

  21. Eggcellent ParachuteProject Procedures • Ensure the parachute is working properly…make any adjustments • Egg must be inspected before attaching to parachute (any cracks and/or rule violations) • Attach egg to parachute • Egg/parachute must be inspected again • Walk to N237 • 1 person from each group will stay in lab and drop the egg/parachute • All other group members will be in the courtyard • After each drop, I will inspect the egg for damage Today

  22. Pre-class Tuesday 2-3-09 Neglecting air resistance, the initial horizontal velocity of a projectile is _____ its final horizontal velocity. a. Greater than • Less than • Equal to • Not related to

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