 # What is Projectile Motion?

## Presentation on theme: "What is Projectile Motion?"— Presentation transcript:

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 flying marble and measure its velocity TEKS 5.A and 5.B

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

Variables Horizontal Vertical Displacement a.k.a. distance x (xf – xi)
y (yf – yi) Initial Velocity Vxi Vyi Average Velocity Va Final Velocity  = Vxi Vyf Time t Acceleration a g = 9.8 m/s2 Angle θ

(Acceleration due to gravity)
Equations X- Component Y- Component Vectors Note: g = 9.8 m/s2 (Acceleration due to gravity)

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

Solving Problems Involving Projectile Motion
Read the problem carefully, and choose the object(s) you are going to analyze. Draw a diagram. Choose an origin and a coordinate system. Decide on the time interval; this is the same in both directions, and includes only the time the object is moving with constant acceleration g. Examine the x and y motions separately.

Solving Problems Involving Projectile Motion
6. List known and unknown quantities. Remember that vx never changes, and that vy = 0 at the highest point. 7. Plan how you will proceed. Use the appropriate equations; you may have to combine some of them.

Group Practice Interactive projectile motion calculator
Other explanations and practice problems

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 Part b Part c

See handouts, other presentations, or textbook examples

Applications Any Ideas?

Summary of Concepts A projectile is any object upon which the only force is gravity, For our purposes we will not consideration air resistance, so we will take the approach all bodies fall at the same rate regardless of their mass Projectiles travel with a parabolic trajectory due to the influence of gravity, There are no horizontal forces acting upon projectiles and thus no horizontal acceleration, The horizontal velocity of a projectile is constant (a never changing in value), There is a vertical acceleration caused by gravity; its value is 9.8 m/s/s, down, The vertical velocity of a projectile changes by 9.8 m/s each second, The horizontal motion of a projectile is independent of its vertical motion.

Independent Practice – problem sets Set 1 Set 2 Set 3

Labs CPO Manual B-1: Launch Angle vs. Range
B-2: Launch Angle vs. Speed B-3: Analysis of Range and Speed

Acknowledgements gk12.poly.edu/.../RAISE...PowerPointFiles/Projectile%20Motion.ppt