In a table compare between one dimensional motion and 2D LI: 1. To describe the relationship between horizontal and vertical motions of a projectile. 2. To describe the factors that affects the projectile motion. SC: Drawing the motion diagram. Vocab: projectile, trajectory Projectile Motion If you observed the movement of a golf ball being hit, a frog hopping, or a free throw being shot with a basketball, you would notice that all of these objects move through the air along similar paths. Each path is a curve that moves upward for a distance, and then, after a time, turns and moves downward for some distance. This curve is called a parabola. An object shot through the air is called a projectile. LI: 1. To describe the relationship between horizontal and vertical motions of a projectile. 2. To describe the factors that affects the projectile motion. SC: Drawing the motion diagram. Vocab: projectile, trajectory Projectile Motion if you ignore air resistance all objects, move through the air only under the force of gravity, after being thrown The force of gravity is what causes the object to curve downward in a parabolic flight path. Its path through space is called its trajectory. LI: 1. To describe the relationship between horizontal and vertical motions of a projectile. 2. To describe the factors that affects the projectile motion. SC: Drawing the motion diagram. Vocab: projectile, trajectory Independence of Motion in Two Dimensions If two baseball players are tossing balls to each other If you are standing behind one of the players you would see it go up and back down (vertically). If you are watching from a hot-air balloon above the field, you would see a horizontal motion. The motion of a projectile is a combination of both. LI: 1. To describe the relationship between horizontal and vertical motions of a projectile. 2. To describe the factors that affects the projectile motion. SC: Differentiate between free fall and projectile launched horizontally. Vocab: projectile, trajectory In the following figure the red ball was dropped, and the purple was given an initial velocity. Both balls have the same height. Both balls reach the ground at the same time The horizontal motion does not affect its vertical motion they are independent LI: 1. To describe the relationship between horizontal and vertical motions of a projectile. 2. To describe the factors that affects the projectile motion. SC: Drawing the motion diagram. Vocab: projectile, trajectory If a person throws a pebble horizontally it will have an initial horizontal velocity . The horizontal velocity is always constant The horizontal acceleration is zero the vertical velocity of the object increases because the gravity is acting on it. LI: 1. To describe the relationship between horizontal and vertical motions of a projectile. 2. To describe the factors that affects the projectile motion. SC: Drawing the motion diagram. Vocab: projectile, trajectory LI: 1. To describe the relationship between horizontal and vertical motions of a projectile. 2. To describe the factors that affects the projectile motion. SC: Drawing the motion diagram. LI: to discuss the case of projectile launched at an angle. Vocab: projectile SC: Drawing the motion diagram. Projectiles Launched at an Angle -The initial velocity has a vertical component and a horizontal component. - The horizontal velocity is constant and ax=0 -If the object is launched upward, it rises with slowing speed, reaches the top of its path with a speed of zero, and descends with increasing speed. -There is a symmetry in the path, g=-9.8 m/s2 -If launched from y=0 vyi=-vyf LI: to discuss the case of projectile launched at an angle. Vocab: projectile SC: Drawing the motion diagram. Projectiles Launched at an Angle -One is the maximum height, which is the height of the projectile when the vertical velocity is zero . -The other quantity is the range, R, which is the horizontal distance that the projectile travels. Not shown is the flight time (hang time), which is how much time the projectile is in the air. X=vcos θ t LI: to discuss the case of projectile launched at an angle. Vocab: projectile SC: Drawing the motion diagram. The Flight of a Ball A ball is launched at 4.5 m/s at 66° above the horizontal. What are the maximum height and flight time of the ball? LI: to discuss the case of projectile launched at an angle. Vocab: projectile SC: Drawing the motion diagram. The Flight of a Ball Identify the known and unknown variables. Known: Unknown: yi = 0.0 m ymax = ? θi = 66° t=? vi = 4.5 m/s ay = −g LI: to discuss the case of projectile launched at an angle. Vocab: projectile The Flight of a Ball SC: Drawing the motion diagram. LI: to discuss the case of projectile launched at an angle. Vocab: projectile SC: Drawing the motion diagram. LI: to discuss the case of projectile launched at an angle. Vocab: projectile SC: Drawing the motion diagram. Forces from Air So far, air resistance has been ignored in the analysis of projectile motion. While the effects of air resistance are very small for some projectiles, for others, the effects are large and complex. For example, dimples on a golf ball reduce air resistance and maximize its range. The force due to air resistance does exist and it can be important. LI: to discuss the case of projectile launched at an angle. Vocab: projectile SC: Drawing the motion diagram. Forces from Air • Forces from the air can affect the trajectory of an object. vi No Effect from Air Force from Air in Direction of vi the distance crossed by water increases vi Fair vi Force from Air Opposing vi the distance crossed by water decreases. Copyright © McGraw-Hill Education Fair Projectile Motion LI: to discuss the case of projectile launched at an angle. Vocab: projectile SC: Drawing the motion diagram.
