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2D Motion. Combining Motion and Vector concepts. Moving Motion Forward. Velocity, Displacement and Acceleration are VECTORS Vectors have magnitude AND direction So far, direction has been positive and negative. Motion with Vectors.
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2D Motion Combining Motion and Vector concepts
Moving Motion Forward • Velocity, Displacement and Acceleration are VECTORS • Vectors have magnitude AND direction • So far, direction has been positive and negative
Motion with Vectors • Motion concepts combine with Vector concepts to allow us to represent motion in multiple directions simultaneously • Two (2) major concepts will be addressed: • 1. Moving in two directions at once (e.g. projectiles) • 2. Moving with respect to (wrt) a non-stationary object (“relative” motion)
How High – How Far • 2nd significant project of semester • Launch an object • Measure distance and time • Calculate everything else • Take video or pictures • Upload to Gaggle or Edmodo (zdm2ni) • Two daily grades (undroppable) • Due Tuesday, October 29th
Projectile Motion • Two-dimensional motion of an object • Vertical • Horizontal
Projectiles • Airborne objects that move as a result of their own inertia and gravity. • They exhibit two dimensional motion. • Horizontal and vertical motion • Horizontal and vertical motion are independent of one another. • The resultant motion is a combination of horizontal and vertical motion.
Components of Projectile Motion • Projectiles have: • vertical velocities that increase and decrease because they are influenced by gravitational forces. • horizontal velocities remain constant because they are not influenced by gravitational forces.
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
Simulators and examples • Music analogy • http://www.geogebra.org/en/upload/files/nikenuke/projectile06d.html • http://www.cs.utah.edu/~zachary/isp/applets/Cannon/Cannon.html
Velocity “Splits” • Have a fixed starting velocity • Splits between X and Y initial velocities using “Triangle” rules
VTOTAL VY Horizontal (X) motion θ VX • X-distance is called “Range” • Moves at constant velocity/speed/rate • i.e. ZERO acceleration
VTOTAL VY Vertical (Y) Motion θ VX • Y-direction called “Height” • Y velocity changes (accelerates) because of Gravity (g) = - 9.8 m/s2≈ -10 m/s2 • Y velocity (speed) “stops” (=0) at “top” of trajectory • Returns to same “magnitude” but different sign when returns to “launch level”
Horizontally Launched Projectiles • Rolls off table/cliff • Thrown/Fired Horizontally • Launch angle = 0º • ALL initial velocity is in X direction • Vy-initial = 0
Horizontally Launched Projectiles • Equations Simplify
Horizontally Launched ProjectilesSample Problem • A dart gun is fired from a 1.9 meter table and lands 2.8meters from the table. • What is the “muzzle velocity” of the dart gun? • How far would the dart travel if fired from 2.3 m?
Horizontally Launched ProjectilesSample Problem • A dart gun is fired from a 1.9 meter table and lands 2.8meters from the table. • What is the “muzzle velocity” of the dart gun? • How far would the dart travel if fired from 2.3 m?
Equations – X and Y components • X- Component • Y- Component Note: acceleration due to gravity is
Equations • X- Component • Y- Component • Vectors Note: acceleration due to gravity is
Strategies for Applying Kinematic Equations in 2 Dimensions • Make a drawing of the situation. • Decide which directions to be called positive and negative. Do this for both the x and y directions. • Remember that the time variable is the same for both x and y. • Make note of all the assumed information. • Starts at rest. • Stops • When motion is divided into two segments, remember the final velocity for one segment becomes the initial velocity for the next segment. • Keep in mind there might be two possible answers form the same problem. Choose the answer that matches the physical situation at hand.
Factors Affecting Projectile Motion • What two factors would affect projectile motion? • Angle • Initial velocity Initial Velocity Angle
Launch Angle • Launch Angle to maximize distance is 45° • Complementary angles (add up to 90°) will launch to the same horizontal distance
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?
Applications Any Ideas?
Solution • Part a • Part b • Part c