## Trajectory - Horizontally Launched Projectiles - Directions

### How it Works:

The Trajectory - Horizontally Launched Projectiles Concept Builder is quite simple to use. You have to do the same three tasks for each of the problems. First you will have to select the proper motion diagram with accurate velocity vectors. There are seven choices to choose from. Thumbnail images of these choices are shown at the bottom of the Concept Builder. When you tap on a choice, the thumbnail image is highlighted and the image appears on the diagram. Tap until you find the image that you like. Then tap on the Select This Diagram. You will be given immediate feedback. If you are wrong, then your Health bar will be updated and you can try again. Once you are correct, you will have to accomplish the second task.

The second task involves determining the numerical values of the horizontal and vertical velocities (in m/s) at 1-second intervals during the projectile's trajectory or path to the ground. This involves filling in the table of x- and y-velocities at times of 1 second, 2 seconds, 3 seconds, and 4 seconds. Be sure to use a negative sign for any downward (or leftward) velocity. Once you have completed the table, tap on the Check Answers button. Feedback will be immediate and the Health Bar is updated. Any incorrect or incomplete table cells will be marked with a red dot. You can correct these values and try again. Your Health bar is updated after every tap on the Check Answers button. Use the Help Me! button if you have difficulty. Once you're velocity values are complete and accurate, you will be able to work on the third task.

The third task is similar to the second task. You will have to determine the numerical values of the horizontal and vertical positions (in m) at 1-second intervals during the projectile's trajectory. Values can be entered into the table. The initial position is the 0, 0 position or origin So any position to the left or below the initial position will be a negative position. As such, you will need to use some negative signs on some of your answers. Once you have completed the table, tap on the Check Answers button. Feedback is immediate. The Health Bar is updated. Incorrect or incomplete table cells are marked with a red dot. You can correct these values and try again. Your Health bar is updated after every tap on the Check Answers button. The Help Me! button will be a useful resource if you have difficulty.

Once all three tasks are completed, your Health bar and progress is shown on a separate screen. After the completion of the second problem, you may be done. It all depends upon how you have been doing. Behind the scenes calculations detect your Health and your improvements. If you are doing well and/or improving from one problem to the next, then you will be done with the Concept Builder and awarded the medal. Otherwise, you may have to do all five problems. Each problem is the same with the exception of the initial horizontal velocity.

### Getting Help

You will notice that there is a Help Me button underneath the Progress Report. You should learn to use this feature of the program. It's how you can turn an exercise in answering questions into an exercise in learning. Tapping on the Help Me button will open a page with help that is specific to each task. Of course, the Help pages are only helpful if you read them. So take the time to read them. Each Help page contains four sections: a discussion of the The Basic Idea, a display of the Question your are facing (or a similar question with different numbers), a section titled "How to Think About This Situation", and a set of links to resources in our Tutorial section. You should pay attention to the section titled How to Think About This Situation. You will find what you need to know in the three or four paragraphs of this section. You will also become a better Physics student for doing that. That is, after all, the goal of such an activity as Trajectory - Horizontally Launched Projectiles​.

Thanks for being patient with the Directions. Happy learning!