Projectile Motion1

What is Projectile Motion?

Instructional Objectives: • Students will be able to: – Define Projectile Motion – Distinguish between the different types of projectile motion – Apply the concept to a toy car and measure its velocity

Projectile Motion • Two-dimensional motion of an object – Vertical – Horizontal

Types of Projectile Motion • Horizontal – Motion of a ball rolling freely along a level surface – Horizontal velocity is ALWAYS constant

• Vertical – Motion of a freely falling object – Force due to gravity – Vertical component of velocity changes with time

• Parabolic – Path traced by an object accelerating only in the vertical direction while moving at constant horizontal velocity

Examples of Projectile Motion • Launching a Cannon ball

Equations • X- Component x f = xi + v xi t

• Y- Component

1 2 y f = y i + v yi t − gt 2 2 2 v yf = v yi − 2 g∆y v yf = v yi − gt

• Vectors

v xi = vi cos(θ ) v yi = vi sin(θ )

Note: g= 9.8 m/s^2

Factors Affecting Projectile Motion • What two factors would affect projectile motion? – Angle – Initial velocity

Initial Velocity Angle

Class Exercise An object is fired from the ground at 100 meters per second at an angle of 30 degrees with the horizontal Calculate the horizontal and vertical components of the initial velocity After 2.0 seconds, how far has the object traveled in the horizontal direction? How high is the object at this point?

Solution • Part a

( s )(cos 30 ) = 87 m s = v sin θ = (100 m )( sin 30 ) = 50 m s s

vix = vi cos θ = 100 m viy

• Part b

0

0

i

∆x vix = ∆t

(

∆x = v x t = 87 m

• Part c ∆y = viy ∆t +

s

)( 2.0s ) = 174m

( ) (

)

(

)

1 1 2 g ∆t 2 = 50 m ( 2.0 s ) + 9.8 m 2 ( 2.0 s ) s s 2 2

Applications

Any Ideas?

LAB TIME!!!