Free Fall and Projectile Motion

• Science, Quarter 4, Week 1
• The lesson will cover free fall and projectile motion.

Free Fall

• Free fall happens when an object is falling under the influence of gravity alone.
• A falling object is in free fall when it is free of all restraints and falls under the influence of gravity alone,
• Motion is classified as free fall motion.
• Objects are called free falling objects.

Characteristics of Free-Falling Objects

• Free-falling objects do not encounter air resistance.
• All free-falling objects on Earth accelerate downwards at a rate of 9.8 m/s².
• The acceleration of free-falling objects is known as the acceleration due to gravity.
• The numerical value for the acceleration of gravity is most accurately known as -9.8 m/s².
• Free-falling objects are acted upon by gravity (force) alone.
• According to Newton's Law of Acceleration, the object's acceleration follows the direction of the net force.
• In free fall motion the net force equals gravity, thus the object follows the direction of gravity which is “downward".
• Acceleration due to gravity g is the vector quantity -9.8 m/s².
• Acceleration due to gravity is constant for a particular location on Earth.
• Freefall is a special case of motion with constant acceleration because acceleration due to gravity is always constant and downward.
• Applicable to free fall motion, the equations for uniformly accelerated motion, replacing "a" with “g”.
• Each successive second of an object's rate increases by 9.8 m/s.

Velocity

• When an object is thrown up in the air, the objects's velocity is initially upward.
• Gravity pulls the object toward the earth with a constant acceleration g; the magnitude of velocity decreases as the ball approaches maximum height.
• At the highest point, the object changes its direction of motion from upward to downward; the ball has zero velocity and the magnitude of velocity increases again as the ball falls back toward the earth.
• The object slows down at the rate of 9.8 m/s² during the upward part of its motion.
• Instantaneous speed at points of equal elevation in the path is the same whether the object is moving upward or downward.
• Velocities are opposite because they are in opposite directions.
• The downward velocities have a negative symbol, meaning that they are moving downward.
• Acceleration from gravity is always constant and downward.

Projectile Motion

• Projectile motion is the motion of an object thrown or projected into the air with a constant initial velocity that follows a curved path.
• A body with an initial velocity that then follows a direction entirely determined by the effects of gravity and air resistance is referred to as a projectile.
• The curve path followed by the projectile is called trajectory.
• The maximum horizontal distance that a projectile covers is called the range (R).
• Projectile motion is two-dimensional with a horizontal and vertical dimension.
• This is along the x and y-axis.
• These two motions are independent of each other.

Motion of a Projectile

• The horizontal motion of the projectile is unaffected by the presence of gravity.
• Gravity works downward and is unable to change the horizontal motion.
• Gravity causes the projectile to accelerate at a constant rate.
• The acceleration of the projectile is equal to the acceleration due to gravity g (-9.8).
• Because there is only a vertical force (gravity) acting upon a projectile, it does not accelerate horizontally; thus, ax equals zero.
• Free fall equations are applied to the vertical motion of the projectile.
• Projectile motion is a combination of horizontal motion with constant velocity and vertical motion with constant acceleration (g).