Vocabulary Review Directions: Read each sentence/phrase below. Identify the correct vocabulary word/s from the word box. Range Force Projectile Acceleration Symmetric Vertical Motion Negligible Gravity Velocity Inertia Horizontal mMotion Speed Projectile mMotion mMotion Trajectory 1. An object upon which the only force acting is gravity. 2. The time rate of change of position plus the direction; displacement divided by time 3. Defined as the time rate of change of velocity. 4. The time rate of change of position; distance divided by time 5. A force that attracts a body towards the center of the earth, or towards any other physical body having mass 6. The projectile travels at a constant speed horizontally 7. Projectile is controlled by force of gravity and it accelerates downward 8. The force is so small that it's effect is of no consequence to the entire phenomenon. 9. The motion of an object thrown or projected into the air, subject to only the acceleration of gravity 10. The curved path of the object in respect to its motion along with the gravity. 11. Made up of exactly similar parts facing each other or around an axis. 12. The distance between the launch point and the point where the projectile hits the ground 13. A change in the position of an object with reference to time 14. A push or a pull upon an object resulting from the object's interaction with another object 15. Described as tendency to resist changes in their state of motion. DISCUSSION Defining Projectiles A projectile is an object upon which the only force acting is gravity. There are a variety of examples of projectiles. An object dropped from rest is a projectile (provided that the influence of air resistance is negligible). An object that is thrown vertically upward is also a projectile (provided that the influence of air resistance is negligible). And an object which is thrown upward at an angle to the horizontal is also a projectile (provided that the influence of air resistance is negligible). A projectile is any object that once projected or dropped continues in motion by its own inertia and is 1] A Horizontal Motfion Vertical Mofion Forces (Present? - Yes or Noj (If present, what direction?) Acceleration (Present? - Yes or No) (If present, what direction?) Velocity Constant or Changing? B. Directions: Study the figures/diagrams. Answer the given questions below. Situation 1: A baseball is dropped off a cliff and it accelerates to the ground at a rate of -9.8m/s2, down. Meanwhile a cannonball is launched horizontally from a cannon with a horizontal speed of 20my/s. a. Trace a line to indicate the trajectory of the cannonball b. Which of these two balls strike the ground first? c. Compare the two diagrams the vertical free-fall motion on the Iett and the two- dimensional free-fall motion on the right. Describe the effect on an object's vertical motion. T=dA n Situation 2: If it takes a projectile 4 seconds to rise to its peak, it will take a total of to move through the air from start to finish. Situation 3: Four identical projectiles are launched with the same initial speed, v, but at various angles above the level ground. Which diagram represents the initial velocity of the projectile that will have the largest total horizontal displacement? (Neglect air resistance). Situation 4: Two stones, A and B, are thrown horizontally from the top of a cliff. Stone A has an initial speed of 15 meters per second and stone B has initial speed of 30 meters per second. Compared to the time it takes stone A to reach the ground, the time it takes stone B to reach the ground is (1) the same (3) half as great (2) twice as great (4) four times as great (Note: negative sign means a downward motion) EVALUATION/POST TEST A. Multiple Choice Directions: Choose only the appropriate letter of your answer. Write your answer in your notebook/Answer sheet. 1. A bullet is fired at an angle of 45. Neglecting air resistance. what is the direction of acceleration during the flight of the bullet? a. upward c. dependent on the initial velocity b. downward d. at a 45 angle 2. A golfer drives her golf ball from the tee down the fairway in a high arcing shot. 'When the ball is at the highest point of its flight: a. the velocity and acceleration are both zero b. the x-velocity is zero and the y-velocity is zero c. the x-velocity is non-zero, but the y-velocity is zero d. the velocity is non-zero, but the acceleration is zero 3. A bullet is fired horizontally from a gun. At the same time a similar bullet is dropped from the same height. The fired bullet will: a. hit the ground first c. hit at the same time as dropped bullet b. hit the ground second d. never hit the ground 4. A pitcher requires about 0.2 seconds to throw a baseball. If the ball leaves his hand with a speed of 80m/s, how large is its acceleration? a. 40m/s b. 40m/s2 c. 400m/s2 d. 400 m/s 5. Which of the following statements about projectile motion is true (neglecting air resistance)? . The horizontal and vertical motions are independent. b. The force on the projectile is constant throughout the flight. c. The acceleration of the projectile is constant throughout the flight d. All of the above statements are true. 6. In projectile motion the a. acceleration is parallel to the velocity. b. acceleration is perpendicular to the velocity. c. acceleration is vertical, while the velocity can be in any direction. d. acceleration is vertical and the velocity is horizontal. B. True or False Directions: Write T if the statement is true, and F if it is false. 7. The horizontal velocity of a projectile is constant. 8. Projectiles travel with a parabolic trajectory due to the influence of gravity. 9. The horizontal motion of a projectile is dependent of its vertical motion. 10. There are no horizontal forces acting upon projectiles and thus no horizontal acceleration. 11. A velocity is any object thrown horizontally or vertically upon which the only force acting is gravity. C. Fill in the blank Directions: Write the appropriate word/s to complete the idea. 12. Relationship between angles and the height: As the angle increases, the also increases. 13. Relationship between the angle and the range: If the angle is less than the range is decreasing. 14. Relationship between the angle and the time: As the angle increases, the time 15. Maximum is achieved if the projectile is fired at an angle of 45 relative to level ground