Free-Fall & Projectiles

Free-Fall Any object which is being acted upon only by the force of gravity is said to be in a state of free fall Free-falling objects do not encounter air resistance On Earth, only approximate free-fall is possible All free-falling objects on Earth accelerate downwards at a rate of 9.81 m/s 2

Any object which is being acted upon only by the force of gravity is said to be in a state of free fall

Free-falling objects do not encounter air resistance

On Earth, only approximate free-fall is possible

All free-falling objects on Earth accelerate downwards at a rate of 9.81 m/s 2

A tennis coach, a ball machine, and a tennis racquet are dropped from the umpire chair. As free-falling objects, they will both hit the ground at the same time.

Conditions under Free-Fall The object is relatively heavy compared to its size. The object falls for a relatively short time period. There is no extra applied force to the free-fall.

The object is relatively heavy compared to its size.

The object falls for a relatively short time period.

There is no extra applied force to the free-fall.

Projectiles A projectile is an object upon which the only force acting is gravity

A projectile is an object upon which the only force acting is gravity

Examples of Projectiles An object dropped from rest An object thrown upward vertically An object thrown upward at an angle

An object dropped from rest

An object thrown

upward at an angle

Projectile Motion projectile travels with a constant horizontal velocity and a downward vertical acceleration. When serving a ball, acceleration occurs only in the vertical direction. It moves at a constant horizontal velocity. This is what causes it to have a parabolic trajectory.

projectile travels with a constant horizontal velocity and a downward vertical acceleration.

When serving a ball, acceleration occurs only in the vertical direction. It moves at a constant horizontal velocity. This is what causes it to have a parabolic trajectory.

X-axis vs. Y-axis There are the two components of the projectile's motion horizontal motion vertical motion Since perpendicular components of motion are independent of each other, they have to be discussed separately.

There are the two components of the projectile's motion

horizontal motion

vertical motion

Since perpendicular components of motion are independent of each other, they have to be discussed separately.

X-Axis vs. Y-Axis When a tennis ball is served, the horizontal velocity is constant, but the vertical motion is the acceleration due to gravity. These two motions are completely separate from each other.

When a tennis ball is served, the horizontal velocity is constant, but the vertical motion is the acceleration due to gravity. These two motions are completely separate from each other.

Rita is a ball girl during Tamara’s match that she is losing. When Rita rolls the ball along the horizontal surface of the court, the ball’s velocity will remain constant. When Tamara drops the ball in preparation for a serve, the ball will accelerate downwards and cover a greater vertical distance each second.

Rita is a ball girl during Tamara’s match that she is losing. When Rita rolls the ball along the horizontal surface of the court, the ball’s velocity will remain constant. When Tamara drops the ball in preparation for a serve, the ball will accelerate downwards and cover a greater vertical distance each second.

A ball served horizontally will hit the ground at the same time as a ball dropped at the same time from the same location. Ex: Rita and Tamara both try to underhand serve from the baseline at the same time. The beauty of the underhand serve is that the ball never touches the ground. Rita hits the ball, but Tamara somehow misses. When the balls land on the ground, they will hit at the same time.

A ball served horizontally will hit the ground at the same time as a ball dropped at the same time from the same location.

Ex: Rita and Tamara both try to underhand serve from the baseline at the same time. The beauty of the underhand serve is that the ball never touches the ground. Rita hits the ball, but Tamara somehow misses. When the balls land on the ground, they will hit at the same time.

THE END!