A thrown ball has left the hand. A coin has been nudged off a shelf. A rock has slipped from a climber's grip. Each is in flight, and for each, gravity is the only force acting on it.
The flights that pass the last lesson's sort form one family, and the family has a name.
The ball, the coin, and the rock share one condition: each is in flight with gravity as the only force acting on it.
An object in flight with gravity as the only force acting on it is called a projectile.
The name starts the moment the object is launched or released. The throw ends, the hand's force ends, and the ball becomes a projectile.
The name holds whatever the direction of motion. A projectile can be rising, falling, or moving sideways.
Air resistance is ignored, here and in every projectile lesson.
Which of these is a projectile?
A flight that fails the sort is not a projectile. The rocket with its engine firing is in flight, but the engine's force acts on it, so it is not a projectile.
The same rocket after burnout passes the sort: gravity alone acts on it, so the coasting rocket is a projectile.
What must be true of every projectile?
A diver has left the diving board and is in the air above the pool. Air resistance is ignored. Is the diver a projectile?
Once the diver leaves the board, nothing touches her.
So gravity is the only force acting on her.
An object in flight with gravity as the only force acting on it is a projectile.
Yes: from the moment she leaves the board, the diver is a projectile.
An object in flight with gravity as the only force acting on it is called a ___. Type the name.
Which of these is a projectile?
Which statement about projectiles is true?
A pitcher throws a fastball. At which moment does the ball become a projectile?