Horizontal and Vertical Motions of a Projectile _ Grade 9 Science Quarter 4 Week 1(360P)
Overview of Projectile Motion
Introduction to the topic of horizontal and vertical motions of a projectile.
Learning objective: Describe the horizontal and vertical motions of a projectile.
Newton's Second Law of Motion
Review of Newton's second law of motion, the law of acceleration.
Definition: The net force is equal to the product of the mass of the object and its acceleration.
Activity on Newton's Second Law
Completing the statement about acceleration:
"The acceleration of an object produced by a net force is directly proportional to the net force and inversely proportional to the mass."
Key Concepts
Larger force applied results in larger acceleration.
Acceleration may vary over time due to various factors.
Uniformly Accelerated Motion (UAM)
Importance of traffic enforcers in maintaining speed limits and road safety, preventing uniform acceleration.
Acceleration is the rate of change in velocity over time, a vector quantity.
Factors influencing acceleration in vehicles.
Examples of UAM
Definition of uniformly accelerated motion:
Velocity changes at a constant rate.
Example: The motion of a vehicle speeding up with a constant rate of increase in speed.
0 acceleration indicates uniform motion.
Effects of Gravity on Objects in Motion
Objects thrown upward eventually fall back due to gravity.
Effect of gravity (9.8 m/s²):
Common for all objects regardless of mass or weight.
Objects in free fall also exhibit uniformly accelerated motion.
Importance of Gravity
Objects accelerate at 9.8 m/s² towards Earth's center.
Example: Dropping an object demonstrates acceleration due to gravity.
Analyzing Motion through Examples
Analyzing various scenarios to determine if they exhibit uniformly accelerated motion (UAM).
Examples include:
A bike at rest: Not UAM.
A fruit dropping from a tree: UAM.
Rocks falling from a cliff: UAM.
A truck maintaining constant acceleration: UAM.
Understanding Projectile Motion
Definition: Motion follows a curved path due to gravitational force, characterized as projectile motion.
Components of projectile motion:
Horizontal motion (x component):
Negligible air resistance,
Constant horizontal velocity (represented as Vx).
Horizontal acceleration is 0.
Vertical motion (y component):
Gravity acting as the force of acceleration (represented as g or Ay).
Constant vertical acceleration of -9.8 m/s² (negative indicating downwards).
Trajectory
Trajectory: The curved path through which the projectile moves.
Example: Moving a rattan ball in a game, showing parabolic trajectory due to gravitational effect.
Example Problem: Horizontally Launched Projectile
Scenario: A marble is thrown horizontally.
Initial velocity (Vi) = 1.50 m/s,
Horizontal distance (dx) = 0.70 m.
Problem-solving Steps
Calculating Time (t):
Formula: t = dx / Vi.
Result: t = 0.47 seconds.
Finding Height (dy):
Formula: dy = 0.5 * g * t².
Result: dy = 1.08 meters.
Calculating Final Velocity (Vf):
Resolving vertical and horizontal components, then using Pythagorean theorem to find the resultant velocity.
Results for components:
Vfy = -4.6 m/s (downward),
Vfx = 1.50 m/s.
Resultant Velocity (Vr) = 4.84 m/s.
Conclusion
Presentation concludes the topic of projectile motion and UAM with activity highlights.
Encouragement to engage with video content and practice problem-solving.
Shout Outs
special acknowledgments to students and contributors such as ojiz vlog, Gab Kalugdan, Creacom, Ma'am Marisol Morpheel, and Biyahuwan City Science and Technology Education Center.