Horizontal Projectiles

Horizontal Projectiles

By TROB

What is a projectile?

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

• So what is a HORIZONTAL Projectile?

• A projectile that is launched horizontal to the surface of the Earth. (straight out)

WHY DOES A PROJECTILE TAKE A CURVED PATH?

• 1. Is there anything pushing the projectile once it leaves the cannon?

• 2. What is the only force acting on the projectile (assuming not friction)?

• 3. Which direction is gravity?

• 4. What does gravity do to the speed of the projectile as it falls?

2-D KINEMATICS

• 2-D means that there are 2 sets of variables

• 2 distances (dx and dy)

• 2 velocities (vx and vy)

• x direction is horizontal

• y direction is vertical

Poll

Which would hit the ground first? A bullet fired horizontally from a gun or dropped from the same height?

• From Gun

• Dropped

HORIZONTAL PROJECTILE MATH

Plugging in assumptions (cont.)

What about distance OUT (x direction)

What if I need to find LANDING velocity?

BOTH! Need to ADD VECTORS together....

SO THE HORIZONTAL FORMULAS ARE:

Example Problem:

• A pool ball leaves a 0.60-meter high table with an initial horizontal velocity of 2.4 m/s. Predict the time required for the pool ball to fall to the ground and the horizontal distance between the table's edge and the ball's landing location.

• GIVENS:

• dy = 0.60m

• Vix = 2.4 m/s

• t = ?

So find time......

Another example......

• A soccer ball is kicked horizontally off a 22.0-meter high hill and lands a distance of 35.0 meters from the edge of the hill. Determine the landing velocity of the soccer ball.

• Givens:

• dy = 22.0 m

• dx = 35.0 m

• R = ?

• Need to find Vfx and Vfy

Solve....

More Solving......

MORE Solving......

Fill in the Blanks

A ball is kicked horizontally off an 80.0 m tall cliff at 8.00 m/s. How far out did it land?