Unit 05 Projectile Motion Relative Motion

What about “relativity” Something may seem like “1-d” to you, but really be moving in “2-d” This is a fight that kept scientists up at night in the 1600s and 1700s … – If the Earth was moving … when we drop something, shouldn’t it land behind us? – Likewise, if I’m in a moving car, shouldn’t a piece of gum I drop land behind me?

Let’s Analyze some Video Footage Ms Bucci and the Truck! View the videos from the webpage. Under the “Video” section choose 1. Throw Ball (Camera in Truck) 2. Throw Ball (Camera out of Truck) 3. Drop Ball from moving truck

Frame of Reference Notice that when Ms Bucci threw the ball up into the air you could view it differently depending on where the cameraman was sitting. This is called a “frame of reference”. It’s the reference point the observer has relative to the object in motion. Are they both moving? Is one moving is one staying still? – We will investigate this more next time!

Basic Ideas The ball is actually moving in 2-dimensional – BUT if the cameraman timed the ball in flight when she was in the truck with Ms Bucci And then timed it when she was out of the truck… She would have had to get the same amount of time… – Since gravity is responsible for the amount of time the ball is in flight, this is ok! Because the horizontal velocity doesn’t affect the time!

Video Clip: Dropping Objects while Moving causes “Projectile Motion” ectors/pap.cfm ectors/pap.cfm Ball thrown up from a truck. tb.cfm tb.cfm Box dropped from a plane.

If an object is dropped or thrown up while moving horizontally; it becomes a “projectile” [moving in projectile motion]. This is because of it will continue to move in the “X” direction as it also moves vertically. Notice that the projectiles move horizontally with the plane or the car in the above examples. Even though they are moving vertically (up and down), they continue to move at a constant velocity in the “X” direction”

A box is dropped out of a moving airplane. Draw where the box will land relative to the airplane.

The box continues moving in the x-direction as it begins to fall to the ground due to gravity.

A ball is thrown up into the air by a person moving on a cart. Draw the motion of the ball as it is thrown up and falls down into the person’s hand. Explain why the ball moves in projectile motion.

A ball is thrown up into the air by a person moving on a cart. Draw the motion of the ball as it is thrown up and falls down into the person’s hand. Explain why the ball moves in projectile motion. Because it is moving horizontally with the person and the cart. When it is throw up, and it also moving vertically. If an object moves horizontally and vertically at the same time, it is PROJECTILE MOTION.