In projectile motion, the vertical component of the velocity of a particle decreases until it reaches its maximum height, at which point it momentarily becomes zero. This occurs because of the influence of gravity on the motion of the particle.
When a particle is launched into projectile motion, it moves along a curved path determined by its initial velocity and the gravitational force acting on it. The motion can be divided into two components: horizontal and vertical.
The horizontal component of velocity remains constant throughout the entire trajectory, assuming there are no external forces acting horizontally (such as air resistance). This is due to the absence of any force acting horizontally, resulting in a constant velocity.
The vertical component of velocity, on the other hand, is affected by the force of gravity. Gravity acts to accelerate the particle downward, causing its vertical velocity to decrease. As the particle moves upward, against the force of gravity, its vertical velocity gradually decreases until it reaches its maximum height.
At the maximum height, the vertical velocity becomes momentarily zero because the particle momentarily comes to a stop in the vertical direction. However, the horizontal velocity component continues to be constant, ensuring that the particle continues to move horizontally.
After reaching the maximum height, the particle begins to descend, and the force of gravity causes the vertical velocity to increase in the downward direction. This process continues until the particle returns to the ground.
In summary, the disappearance of the vertical component of velocity at the maximum height in projectile motion is a result of the deceleration due to gravity, causing the particle to momentarily come to a stop in the vertical direction before descending.