projectile motion

projectile motion

• a parabolic path formed by a

  • CONSTANT VELO in the x-direction

  • constantly CHANGING velocity in the y-direction

horizontal or x-component of velocity of a ball kicked/thrown at an angle

• stays constant for the entire trip

• same when it hits the ground as when it left the ground

vertical velocity or y-component of velocity of a ball kicked/thrown at an angle

• velocity when it hits the ground has the same magnitude, but negative direction to when it left the ground

• velocity is constantly changing (or accelerating) - getting smaller positive as the object goes up and getting larger negative as the object comes back

why does the velocity change in the y-direction but not in the x-direction (when thrown or kicked)

• an object will not change its motion or accelerate unless a NET FORCE is exerted on it

• the net force and acceleration are in the same direction

• in the y-direction, there is an unbalanced force of GRAVITY

only force on an object in free fall (projectile motion)

• gravity (always directed downward)

• therefore, the ACCELERATION is DOWNWARD

is there acceleration in the X direcion of a ball thrown in the air (projectile motion)

• NO; there is no force except a small amount of air friction in the x-direction

how are the horizontal motion and vertical motion separated; (when ball leaves desk_

• once the ball leaves the desk, its horizontal motion in the x-direction is SEPARATE from its vertical motion in the y-direction

balls velocity in the x-direction as it rolls off the table

• stays the same for its entire trip in projectile or parabolic motion

• it will hit the ground at the same horizontal velocity as when it left the table

balls velocity in the y-direction (of rolling off a table)

• constantly speeds up - accelerates at -9.8 m/s/s the entire trip in projectile or parabolic motion - speeds up vertically as it falls and moves horizontally