Horizontal Velocity:
* No Horizontal Force: In the absence of air resistance, the only force acting on a projectile is gravity, which acts vertically downwards. There's no force acting horizontally.
* Newton's First Law: Newton's First Law of Motion states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. Since there's no horizontal force, the horizontal velocity remains constant.
Vertical Velocity:
* Gravity's Influence: The force of gravity acts continuously on the projectile, pulling it downwards. This force causes a constant acceleration in the vertical direction, known as the acceleration due to gravity (approximately 9.8 m/s²).
* Changing Velocity: Since there's a constant acceleration, the vertical velocity changes continuously. It increases as the projectile goes up (due to gravity acting against its initial upward velocity) and decreases as it comes down (due to gravity accelerating it downwards).
Key Points:
* Neglecting Air Resistance: The explanation above assumes negligible air resistance. In real-world scenarios, air resistance can affect both horizontal and vertical velocity, slowing the projectile down.
* Path of the Projectile: The constant horizontal velocity and changing vertical velocity lead to the characteristic parabolic path of a projectile.
Example:
Imagine throwing a ball horizontally. The ball will travel in a curved path, but its horizontal speed remains constant. The ball will fall vertically downwards due to gravity, causing the vertical velocity to change.
