KINEMATICS IN TWO OR THREE DIMENSIONS
LESSON PLAN
PERIOD #6 Projectiles

MATERIALS:

Projectile gun
metric tape measure

REVIEW:

Summary of what we know about projectile motion.
horizontal velocity is constant - zero acceleration.
vertical acceleration is constant.
horizontal and vertical components of motion are independent of one another.
 

OBJECTIVES:

B: Vector Kinematics in Two Dimensions (Motion with Constant Acceleration)

It is expected that students will apply the concepts of motion with constant acceleration to various real-life situations.

B1.  identify situations involving the use of kinematics

B2.  solve problems involving:

•displacement •initial velocity •final velocity •average velocity •acceleration •time

B3.  describe the shape of the path taken by a projectile fired at some angle above the horizon if friction is negligible

B4.  determine from experimental data that the horizontal motion of a projectile is independent of its vertical motion if friction is negligible

B5.  demonstrate that the horizontal velocity of a projectile is constant if friction is ignored

B6.  state that a projectile experiences a constant downward acceleration due to gravity if friction is negligible

B7.  resolve a projectile's velocity into horizontal and vertical components

B8.  solve projectile motion problems involving:

•range •maximum height •time of flight •displacement •velocity •acceleration

 

GUIDED PRACTICE:

1. Use examples 3-7 and 3-8 to illustrated how the kinematic equations can be applied independently to the vertical and horizontal motions to solve projectile problems.

2. Lab on projectiles; practice problems 1 - 4

INTRODUCTION:

1. Range is defined as the horizontal distance a projectile travels when it returns to its original height.

  • note that to get the maximum range R = dx = vxt you must give the projectile the highest possible horizontal speed and keep the projectile in the air for the longest time. Use vector diagrams and vector components to illustrate that this occurs when the angle is 45¼. Demonstrate using the projectile gun and stream of running water.
  • also using diagrams and the projectile gun or stream of water point out that if the range is not the maximum for th__yat velocity then there will be two different angles that will produce that range.

2. There are some projectile problems that cannot be solved using the kinematics equations that we know in their present form. Take for example - problem 3-9 in your text.

  • show how to derive the Range equation

GUIDED PRACTICE:

Have students determine the angles of the projectile gun to achieve a desired range.

EXERCISE:

Problems #38, 40, 44, 48 and 50

EVALUATION:

Kinematics test next class.

HAND OUT BONUS QUESTIONS FOR KINEMATICS

Preparing for tests