Horizontal Projectiles Physics Mr. Berman

Horizontal Projectiles are launched with a horizontal initial velocity.

Horizontal Projectiles http://www.physicsclassroom.com/mmedia/vectors/hlp.cfm

Remember “Boat and River”

Motion in Two Dimensions http://www.physicsclassroom.com/mmedia/vectors/hlp.cfm

A horizontal projectile from the same height Which falls first? A free falling object Or A horizontal projectile from the same height

A horizontal projectile Which falls first? A horizontal projectile Or A horizontal projectile from the same height with a higher initial horizontal speed

Question A zoologist is aiming at a monkey with a tranquilizer gun. Both are at the same level. The monkey is about to jump. Should the zoologist aim horizontally or low in order to tranquilize the monkey?

Horizontal Projectiles Two dimensional motion Initial velocity is entirely horizontal X-axis : constant velocity Y-axis : constant acceleration

A Look at the Velocities Vx= constant Vyi=0 Vy = a t

Animation http://www.physicsclassroom.com/mmedia/qt/vectors/hlpwin.cfm

Characteristics of Path Trajectory Parabola Range

Equations for Horizontal Projectiles x direction: use any equation for const. velocity motion y direction: use any equation for const acceleration x=vx t ____ y= 1 at2  t= √2y/a 2 vY=at

Example 1 A cannon ball is fired horizontally from the top of a 90 m tall cliff with an initial velocity of 20 m/s. How long did the ball take to reach the ground? What was the range? What was the x and y-velocity of the ball right before it hit the ground? Answer: a)4.3sec , b) 85.7m c) Vx= 20m/s Vy=42m/s 6.32sec 126.5m Vx= 20m/s Vy=63.2m/s

Example 2 A diver dives horizontally out from a 9 m platform with a velocity of 3m/s. How far out did he dive (range)? Answer: t=1.35s, x= 4m T=1.34s x= 2.68m

Projectile Applet http://www.walter-fendt.de/ph11e/projectile.htm