TWO DIMENSIONAL MOTION Chapter 6 Motion in Two

TWO DIMENSIONAL MOTION Chapter 6: Motion in Two Dimensions

Trajectory • After a projectile has been given an initial thrust, if you ignore air resistance, it moves through the air only under the force of gravity. • Force of gravity is what causes it to curve downward. • Its path through space is called its trajectory.

PROJECTILE MOTION • What is a projectile? – Any object shot through the air • How does it travel? – Follows a parabolic path • Assume weight is the only force acting on it • EQUATIONS OF MOTION will change…slightly

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 = vi 2 (sin 2 q)/g • Notice the angle is doubled and the initial velocity is squared • The unit for range is meters (m)

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

Projectiles launched at an angle… • When a projectile is launched at an angle, the initial velocity has a vertical component as well as a horizontal component. • Equations of motions change slightly…now we have to differentiate between x and y components.

Centripetal Acceleration • “center seeking” • 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=v 2/r

Centripetal Force • Force required to keep an object traveling in circular motion: Fc = mac = mv 2/r • Remove force, will travel in a straight line • This is different than the “fictional” force of centrifugal force…which does not exist.

CENTRIPETAL LAB 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.

51. 53. 56. 58. 60. 61. 62. 65. 67. 28. 9 m 3. 2 m 31 m, 212 m Ch 6 14. 3 s, 497 m Homework 11. 8 m/s 9. 65 m/s 2; 5937 N 71 m/s 2, 500 N 18 m/s 1, 470 m

PERIODIC MOTION • Review hw problems • What is periodic motion? • Centripetal force is a “fictional” force • pendulums(equation) • circular motion

PENDULUM LAB • 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

• • 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 Egg Drop Parachute

• • 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 N 237 (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 Eggcellent Parachute Project