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=Week 2 - One-dimensional projectile motion=

**1) Introduction**

 * Last session we were introduced to vectors and how we could use them to visualize quantities exhibiting both size and direction. This session, we will apply those concepts to a real life one-dimensional problem - analyzing falling projectiles. The dimension of interest is the y-axis or up and down in a straight line. Projectiles are objects that are only under the influence of gravity. This is a hard concept for many to grasp as we humans are always grounded... literally, but projectiles exist all around us. Most common projectiles are ** thrown, shot, launched or dropped**.

When we throw a ball, we turn it into a projectile. When we jump up in the air, we turn into projectiles. When a raindrop falls from a cloud, it is a projectile. When we drop stuff off a five-story tower it... **

media type="youtube" key="HVIzaOvnLVY" height="344" width="425" ...becomes a projectile. = //Thought Question 2.1:// //Are there limits to what can become a projectile?// =
 * //Thought Question 2.2://** //How long does it take for the objects to hit the ground?//

In this session, we will learn how to use our standard equations of motion to estimate how long it takes a projectile to hit the ground, what its velocity is at impact, and what launch velocity would be necessary to send it back up to a specified height. Next time you pay money to become a one-dimensional projectile, think about how these equations apply to you.

**2) Review**
Position, velocity , and acceleration are all vector quantities. In physics, they are represented by the variables s, v, and a.
 * //Thought Question 2.3://** //How are// **//s//**//,//**//v//**//, and// **//a//** //related mathematically? What about in your own words and experiences?//

Vectors can be added, subtracted, and even scaled using graphical or numerical means.
 * //Review Question 2.x://** //Is one method of combination easier or better than the other?//

You can compute the length or magnitude of a vector in a similar way that you compute the hypotenuse of a right triangle.
 * //Thought Question 2.5://** //What does this say about how the vectors are related to right triangles?//

** Vote, rank, and discuss them each week! **  Please remember to review and vote on the best student questions from the previous session for inclusion in our year end course guide. The questions are maintained by UserVoice. See sample below.



**3) New Content and Assignment** //6. Newton lays down the laws of force, mass, and acceleration.//


 * //Thought Question 2.6 -//** //Under ideal conditions, such as in a vacuum, all objects fall at the same rate. In the real-world though, what forces affect falling objects?//

http://www.physicsclassroom.com/Class/1DKin/U1L5a.cfm
 * R** **eading**
 * //Thought Questions 2.7//** //- What is the acceleration of gravity? What affects its value?//

http://www.physicsclassroom.com/Class/1DKin/U1L5b.cfm
 * //Thought Questions 2.8//** //- What does it mean to accelerate at 9.8m/s²?//

http://www.physicsclassroom.com/Class/1DKin/U1L5c.cfm
 * //Thought Questions 2.9//** //- What do the graphs of s,v, a look like? How would the shapes of these graphs differ on the moon?//

http://www.physicsclassroom.com/Class/1DKin/U1L5d.cfm
 * //Thought Questions 2.10//** //- What factors affect impact velocity?//

http://www.physicsclassroom.com/Class/1DKin/U1L5e.cfm
 * //Review Questions 2.x// //- What misconceptions did you have about free falling objects?//

Interactive Examples** For this session's interactive example, we are going to lock the simulator at 90º. This will restrict your simulation to the one-dimensional case for simplicity. We will explore more general two-dimensional projectiles in the coming sessions.



Experiment with how various launch velocities and masses affect the total time, max height, and impact velocities of your projectiles.


 * //Review Question 2.x//** //- The colored markings on the graph are drawn at regular time intervals. What does it mean when the markings are closer together? Where are the markings closest? Where are they the farthest apart?//

Use this experiment fact sheet for practice. Fill in the missing variable values by your name from left-to-right. Columns further to the left have a greater degree of freedom, so choose values that you have experimented with and don't repeat values already in the column.


 * //Teacher Crafted Activity 2.x : Inserted Dynamically by Teacher Assignment Administration Page //**

**4) Assignment Submission**
Free fall and return to sender

According to legend, Isaac Newton's apple fell from a tree, hit him on his head, and left him dazed and enlightened! That fall might have been good enough for inspiration 320 years ago, but from what heights must things fall today to enlighten us?

For this assignment, we will experiment with one-dimensional projectile motion by virtually dropping objects from an assortment of heights. You will have to search the Internet to find three interesting locations and heights from which to drop items of your choosing. Selections //must// be unique. Early contributors are at an advantage, so get your selections in early!

Once you have selected what you are going to drop and from where, fill in the worksheet with the requested information using your knowledge of falling objects to support your answers.

Ask questions on the discussion board. media type="custom" key="5695973"
 * Take a quiz to see what you know.**

[insert questions into quiz - remove this once you are done]

1) Which one of these statements is not one of newton's three laws:For every action, there is an equal and opposite reactionF=MAForces must conserve their own existence as long as such conservation does not conflict with the First or Second LawA body in motion, tends to stay in motion2) 2) The acceleration due to gravity can be estimated to be:9.8 m/s/s10 feet/s10 lbs9.8 feet/s 3) Magnitudes of vectors can be computed using:Pythagorean theoremHypocratic oathEureka exclamationPapyrus formula 4) A projectile is an object that is only under the influence of what:magnetismgravitybuoyancynone of the above [insert questions into quiz]

As we do at the end of each session, we will contribute a summary of what we have learned in our own words, images, and links to our personal course review log. The purpose of which is to evolve a review book for the entire course.
 * 5) Personal Learning Log Contributions**

Additionally, each of you will submit three unique questions and answers based on the content learned this session, Make them fun and challenging for your classmates. We will vote on the best ones next session, so be creative!