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Archive for the ‘Horizontally Launched Projectiles’ Category

April 4, 2014 · by physics · Horizontally Launched Projectiles, Physics Videos

A ball rolls horizontally off the edge of a tabletop that is 19.6 meters high. It strikes the ground at a point 6 meters from the edge of the table.

a) How long was it in the air?

b) What was its speed at the instant it left the table?

Raw Transcript

Hello everyone, this is Tom from everystepphysics.com. We’re gonna do a problem that was is in a test and asked from a customer. And relating to path of objects. So, let’s get started. Physics is my key to put in this entry line here in the calculator. To get my menu, you press enter and we’re already at path of objects.
You can see pressure, pressure gauge,pulley, radius, roller coaster; all kinds of things in this menu.
for you to pass your physics test. Path of objects. I gave you three choices. Notice that there’s they ask if they’re angle or if the velocity is given or neither is given. In this case, neither was given. So we’re gonna choose number three. You can scroll down to it or you can press the number before and I like the press the number before. And a course they gave me the the height. His ball is rolling off a table and height of the table is… We have to press alpha before you enter anything in these entry lines here. The height is
Alpha 19.6 You always put that in and I always ask you or give you the choice of what they have entered sometimes you’ll enter inches or feet, or anything. It all changes to meters and in this case meters so we’re going to choose number two. And then the distance along the ground. They say this ball drop 6 meters from the edge in the table. We’re going to press alpha 6 meters. Seemingly a simple problem isn’t it, huh? Initial Heights thats i, initial height, that’s 19.6 meters and the distance is from the table is equal to 6 meters. I’ll show you what you’ve entered so you can change it if you want. I say it’s okay. And they ask you to find the time in a air. Well, that’s the time to the ground 1.999 seconds. Basically two seconds to the ground. here’s the exact equations here. You have to find that before you can find the initial speed. Remember speed is absolute, in other words, you can’t be negative. Velocity is a vector can be negative or positive and shows direction and magnitude. Speed shows magnitude but doesn’t show any direction, etc. And of course the ball rolling off the table has to be plus, can’t be minus. And so the answer is 6.8
meters per second. Pretty neat, huh? everystepphysics.com, go to my site, buy my program and pass your physics class. Very difficult classes. And also subscribe to me so you can see future videos and blog.