(9.8 m/s 2 ) Motion of Every ObjectĪny projectile travels horizontally and vertically. The change in velocity is ALWAYS 9.8 m/s every second. The vertical position of a projectile constantly changes, though. Revisit Our Thinking A B C Which path will the ball follow? How does initial velocity affect the time it takes a horizontally- launched projectile to reach the ground? ” It Doesn ’t! What is the only factor (besides air resistance, which we are ignoring) that DOES affect the time it takes a horizontally-launched projectile to reach the ground? How high off the ground the object is. The title of this slide says it all: horizontal and vertical motion are independent of each other – even when they are happening at the same time! So…let ’s get back to the question: Horizontal and Vertical Motion Don ’t Know Each Other Exist! But… YOUR INTUITION (at least in this case) IS WRONG! Here ’ s a video Observations from the lab Intuition will tell you that the horizontally launched object will “hang” in the air. So what effect did horizontal velocity have on the time it took (the downward motion) the coin to hit the ground? The best conclusion we can make from this is that the horizontal motion of the coin does not affect downward motion of the coin. Observations from the lab In your notes, sketch what the motion of these two coins must have looked likeĪs we saw with the coin launcher, both coins – the one that fell straight down and the one that was flung out horizontally - hit the ground at the same time. The projected coin also moved to the right but it fell downward at exactly the same rate as the dropped coin. So What ’s the Correct Answer?īoth coins fall the same amount vertically in the same amount of time. We’ll revisit the question at the end of these notes. The object will continue to move forwards the entire time it is falling. The object will move forward at first, but will eventually just fall straight down. because some people referred to the coyote in cartoons, the researchers called it the Wile E. The object will stop in midair, and then start to fall straight down. The breakdown of answers they got was almost exactly the same at all ages. Write your prediction on a clean sheet of paper – we will be adding to this at the end of this lesson, so keep it neat! Predictionī A few years ago, researchers went to elementary, middle, and high schools as well as universities and showed students this image and asked them, “ Ignoring air resistance, which of the following correctly shows what an object would do if it rolled off a cliff? Predict A B C Which path will the ball follow?ĭetermine which path you believe the ball will follow AND WHY.
If this red ball had a net force to the right applied to it and rolled off the cliff at a constant speed, what would its path look like? Make a Prediction Today we will: show your completed homework talk about projectile motion begin working on PTG 2.4 (finish for homework) Do BEFORE THE BELL: get out your homework get out your spiral and something to write with We’ll get back to the lab before the end of the period – so leave your lab notebook out and OPEN For now, get out your spiral for notes and a clean sheet of notebook paper for your predictions/reflection Time for Notes Your group will have 20 minutes to complete Part A of the lab (#1 – 4) Time for the Lab! We ’re going to split the lab into two parts. remember: a hypothesis is an “if” “then” statement – and if you’re feeling particularly smart today, add a “because” statement after the “then” Projectile Motion, Part 1 Sec 4 - Projectile Motion, part 1” Don ’t forget to make an entry in your table of contents Copy the question down at the top of your new page How does initial velocity affect the time it takes a horizontally- launched projectile to reach the ground?įorm a hypothesis that addresses the lab question. Turn to the first clean page in your lab notebook and title it, “Chpt 2. As you read, be thinking about: what materials will you be using how the lab will help you answer the question what your hypothesis will be Today ’s Investigation How does initial velocity affect the time it takes a horizontally- launched projectile to reach the ground? Take a few moments and read pg 174 – 175 in your text. Today, we will Conduct an Investigation Take some notes Write a short reflection about what we learned Please Do Now: get your lab notebook get out something to write with Good Morning!
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