Projectiles The only force acting on a projectile

Projectiles The only force acting on a projectile is the force due to gravity (weight).

Projectiles The only force acting on a projectile is the force due to gravity (weight). Fg For our course, we assume that air resistance is negligible. Small enough to ignore b/c the effect is so small.

Projectile trajectories Path

Projectile trajectories

Film the trajectory of a golf ball Parameters: 1. 2. 3. 4. Find the mass of the ball that you are using. The trajectory must be dropped or straight out (horizontally launched). The release height must be the height of the counters. You must ’see’ the ball in the frame from the launch to landing.

Projectile Quiz on Monday

Projectiles Definition: A projectile is an object moving through the air and the only force acting on it is the force due to gravity. Force Diagram for a Projectile: Fg An ob ject in a proj free fall is ectile. A projectile’s path is called its trajectory. The shape of the trajectory is parabolic. The graphic above shows the VELOCITY VECTOR components at various places along the projectile’s trajectory. The horizontal and vertical components of a projectile’s motion are independent of one another. Peak The acceleration of gravity causes the projectile to speed up, slow down or change directions vertically. Height KEY CONCEPT: The acceleration of gravity does not affect the horizontal motion at all! Therefore, the horizontal motion of a projectile is at constant velocity. Range Launch Landing Spec Whe ial case a nap rojec bout the r tile is ange it rea 45 o, launched : ches at the m axim um r ange. 51

Logger. Pro Video analysis Wha t Drop was you r pro ped? jec Laun ched tile’s tra je Strai ght o ctory? ut? • Import your film from last time into • Complete the video analysis of the vertical motion. • Do a curve fit (quadratic) to the data. • Complete the video analysis of the horizontal motion. • Do a linear fit to the data.

Logger. Pro Video analysis • Import your film from last time into • Complete the video analysis of the vertical motion. • Do a curve fit (quadratic) to the data. • Complete the video analysis of the horizontal motion. • Do a linear fit to the data. What was your projectile’s trajectory? Dropped? Launched Straight out? How are the ’y’ plots similar for dropped or launched straight out? How are the ‘x’ plots different for dropped or launched straight out? WHY?

Logger. Pro Video analysis • Import your film from last time into • Complete the video analysis of the vertical motion. • Do a curve fit (quadratic) to the data. • Complete the video analysis of the horizontal motion. • Do a linear fit to the data. What was your projectile’s trajectory? Dropped? Launched Straight out? How are the ’y’ plots similar for dropped or launched straight out? How are the ‘x’ plots different for dropped or launched straight out? WHY?

A B C

A ow h s s h p a t r u g o e t s h e g h i t a r f t o S h d c ? i Wh aunche jectile L pro B a Whic C h of thes e gra Drop phs s ped proje h ctile ow a ?

Great Stuff to know about Projectiles!! Peak Horizontal Motion Vx is constant. ΣFx = 0 Since the horizontal forces are balanced, a projectile is in constant velocity in the horizontal direction. Predictable patterns in Projectile motion. 1. Vertical velocity at the peak is 0. 2. The magnitude of the vertical velocity is the same at symmetrical points on the trajectory, so |Vy. B| = |Vy. D| 3. The horizontal velocity is the same everywhere. 4. The time to go from A to C is equal to the time to go from C to E since A and E are ‘at the same level’. 5. The time to move from A to E is the same when analyzing horizontal or vertical motions. Vertical Motion Vy changes. ΣFy ≠ 0 Since the vertical forces are unbalanced, a projectile accelerates in the vertical direction. Using “INTERVALS’ of motion: Many projectile problems are easier to solve if we analyze the up interval (Launch-to-peak) or down interval (peak –to-landing) instead of launch-to-landing. at le. - th. b i g i l neg ct it ion is can negle t c i r f e at me th all that w u s s a We so sm s it is n a e m 56

X (m) Y (m) Position(meters) Time(seconds)

X (m) Y (m) Position(meters) A Time(seconds) B C D