Roadrunner Facts Roadrunners are prey for hawks, house cats, raccoons, snakes, and skunks, not coyotes! Roadrunners can attain speeds of 17 mph. A roadrunner catches a rattlesnake by the tail, cracks it like a whip and repeatedly slams its head against the ground till dead. Its extreme quickness allows it to snatch a humming bird or dragonfly from midair. http://www.desertusa.com/mag98/sep/papr/road.html

Cartoon Laws of Physics Any body suspended in space will remain in space until made aware of the situation. Everything falls faster than an anvil. All principles of gravity are negated by fear. Any body passing through solid matter will leave a perforation conforming to its perimeter.

2-Dimensional Motion Definition: motion that occurs with both x and y components. Example: Throwing a ball to another person Shooting free throws Each dimension of the motion can obey different equations of motion.

Solving 2-D Problems Resolve all vectors into components x-component Y-component Work the problem as two one-dimensional problems. Each dimension can obey different equations of motion. Re-combine the results for the two components at the end of the problem.

Projectile Motion Something is fired, thrown, shot, or hurled near the earth’s surface. Horizontal velocity is constant. Vertical velocity is accelerated. Air resistance is ignored.

Horizontal Component of Velocity Is constant Not accelerated Not influence by gravity Follows equation: d = Vxt

Horizontal Component of Velocity

Vertical Component of Velocity Undergoes accelerated motion Accelerated by gravity (-9.8 m/s2 down) Vy = Vi,y + gt h = Viyt + 1/2gt2 Vf2 = Viy2 + 2gd

Horizontal and Vertical

Horizontal and Vertical

Zero Launch angle vi A zero launch angle implies a perfectly horizontal launch.

vi General launch angle  You must begin problems like this by resolving the velocity vector into its components.

Resolving the velocity Use speed and the launch angle to find horizontal and vertical velocity components Viy = Vi sin  Vi  Vx = Vi cos 

Projectiles Projectiles have highly symmetric characteristics of motion. It is handy to know these characteristics, since a knowledge of the symmetry can help in working problems and predicting the motion.

Trajectory of a 2-D Projectile x y Definition: The trajectory is the path traveled by any projectile. It is plotted on an x-y graph.

Range of a 2-D Projectile x y Range Definition: The RANGE of the projectile is how far it travels horizontally.

Maximum height of a projectile y Maximum Height Range The MAXIMUM HEIGHT of the projectile occurs when it stops moving upward.

Maximum height of a projectile y Maximum Height Range For a projectile launched over level ground, the maximum height occurs halfway through the flight of the projectile.

Velocity of a projectile x y vx vy vx vy vx vy vx vx vy The velocity can be resolved into components all along its path.

Velocity of a projectile x y vx vy vx vy vx vy vx vx vy Notice how the vertical velocity changes while the horizontal velocity remains constant.

A football player kicks a ball from ground level with a velocity of 40m/s at 30o above the ground. A.) what is the hang time of the ball? B.) what is the distance the ball travels? C.) what is the max height?