For each diagram below, create a free diagram of the ball at the top

of the path

As you view the following video and animation think about the forces in your

free body diagrams 2-D Motion

Independence of Motion

• Notice that the veridical motion of the projected ball is identical to the vertical motion of the falling ball

• Notice that the projected ball travels forward at constant speed

Horizontal Component of Velocity

• Is constant

• Not accelerated

• Not influenced by gravity

• Follows equation: dx = Vixt + 1/2axt2

0

Vertical Component of Velocity

• Undergoes accelerated motion

• Accelerated by gravity (9.8 m/s2 down)

• Vfy = Viy + at

• dy = Viyt + 1/2ayt2

• Vfy2 = Viy

2 + 2aydy For all y-direction projectile equations

a=g

Perpendicular components of motion are independent of each other

Independence of Motion

Please visit the Physics Zone Projectile Motion Lesson “Archer in Truck: Proof III”at sciencejoywagon.com to access this video.

x y

Vi

Vf

v

v

a

d

t

This may be a useful way to organize your data. Remember to solvex variables with x variables and y variables with y variables….

TIME links the x and y variables

Projectile fired at an angle

• As you view this video, notice the independence of motion.

• Notice that the vertical acceleration is downward and constant– The ball “slows” during ascent and “speeds up” during

descent

• When angles are involved, the appropriate components of velocity must be used and the sign used to indicate the direction of velocity and acceleration is very important

A bouncing ball captured with a stroboscopic flash at 25 images per second.

MichaelMaggs Edit by Richard Bartz