What is Projectile Motion?

1. What is Projectile Motion?

2. Instructional Objectives: • Students will be able to: • Define Projectile Motion • Define Trajectory • Characteristics of a projectile's motion • Horizontal and vertical components of velocity and displacement • Initial velocity components • Examples of problems

3. Projectile Motion • A projectile is an object upon which the only force acting is gravity. A projectile is any object which once projected or dropped continues in motion by its own inertia and is influenced only by the downward force of gravity (neglecting air resistance). • A trajectory is the path followed by a projectile. The shape is a parabolic curve. • -Its path is determined by gravitational acceleration. The motion is in two-dimensions • Vertical • Horizontal

4. 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

5. Examples of Projectile Motion • Launching a Cannon ball

7. Horizontal Projectile

8. Equations • X- Component • Y- Component • Vectors Note: g= 9.8 m/s^2

9. Class Exercise A ball is projected horizontally from the edge of a table that is 0.862m high, and it strikes the floor at a point 1.42m from the base of the table. The acceleration of gravity is 9.8m/s2. What is the initial speed of the ball?

10. Explanation: • Choosing the edge of the table as the origin of our coordinate system, we have • y= viy(t) - 1/2g(t)2 • With viy = 0 so that • y=-1/2g(t)2

11. Class Exercise Cont’d • A toy car runs off the edge of a table that is 1.066 m high. The car lands 0.5632 m from the base of the table. • How long does it take for the car to fall? • The acceleration due to gravity is 9.8 m/s2. • What is the horizontal velocity of the car?

12. Summary • 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 value), • There is a vertical acceleration caused by gravity; its value is 9.8 m/s/s, down, • The vertical projectile is any object upon which the only force is gravity, • 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.

13. Practice TIME!!!