Projectile Motion Part 1| Grade 9 Science Quarter 4 Week 1 Lesson
Short Summary:
This Grade 9 Science lesson introduces projectile motion, focusing on the horizontal and vertical components of motion. Key points include Newton's Second Law, uniformly accelerated motion (UAM), and the effects of gravity. Specific examples like a coin toss, a diving man, and a sepak takraw game illustrate projectile trajectories (parabolas). The lesson details the calculation of projectile motion, using a marble rolling off a table as a worked example, demonstrating how to calculate height and final velocity. The applications are understanding the motion of objects under gravity, and the implications are in understanding various real-world scenarios involving thrown or launched objects. The lesson uses formulas and calculations to explain the concepts.
Detailed Summary:
The lesson begins by reviewing Newton's Second Law of Motion and uniformly accelerated motion (UAM), using examples of traffic enforcers maintaining constant speed limits and a vehicle accelerating at a constant rate. The concept of constant acceleration is emphasized, contrasting it with non-uniform acceleration. The role of gravity in UAM is explained using the example of a coin toss and climbing stairs, highlighting that gravity causes objects to accelerate downwards at 9.8 m/s². Several scenarios are presented to identify examples of UAM (e.g., a falling fruit vs. a stationary bike).
The core concept of projectile motion is introduced, defining it as motion along a curved path due to gravity. The lesson distinguishes between horizontally launched and angled-launched projectiles, using examples of a diving man and a sepak takraw game. The horizontal and vertical components of projectile motion are explained separately. Horizontal motion is characterized by constant velocity (no acceleration), while vertical motion is characterized by constant downward acceleration due to gravity (9.8 m/s²). The terms "range" (horizontal distance) and "height" (vertical distance) are defined.
A detailed example problem is solved, involving a marble rolling off a table. Given the horizontal distance and initial velocity, the lesson demonstrates how to calculate the height of the table and the final velocity of the marble just before it hits the ground. The calculations involve using kinematic equations and solving for time first, then using that time to find the height and final velocity. The formulas used are explicitly shown and explained step-by-step. The negative sign in the final velocity calculation is interpreted as indicating the downward direction.
Finally, the lesson concludes with shout-outs to various individuals and organizations.