Go to http://phet.colorado.edu/simulations/sims.php?sim=Motion_in_2D and click on Run Now.

1) Once the simulation opens, click on ‘Show Both’ for Velocity and Acceleration at the top of the page. Now click and drag the red ball around the screen. Make 3 observations about the blue and green arrows (also called vectors) as you drag the ball around.

-If I move the red ball upwards or downwards in a straight line, the arrows move in an opposite way.

-When I move the ball in a almost perfect circle, it looks like the arrows form a 90 degree angle, or a right angle.

-Now if I move the ball left or right, the green arrow pops out first, then the blue arrow follows, but later goes the opposite way, while the green only came out once.

2) Which color vector (arrow) represents velocity and which one represents acceleration? How can you tell?

-Velocity is the green arrow because of the speed and acceleration blue because it was going the opposing side of velocity, and because it also went towards velocity, but always coming back the opposite way depending which direction you moved the red ball. Also the acceleration declines according to the velocity, which is why the blue arrow is also acceleration.

3) Try dragging the ball around and around in a circular path. What do you notice about the lengths and directions of the blue and green vectors? Describe their behavior in detail below.

-As you move the ball in a circular path, the green arrow, or velocity, has the longest length while the blue arrow, acceleration, has the smallest length, and they form just right angles as you move in a circle. The acceleration stays the same while the velocity changes.

4) Now move the ball at a slow constant speed across the screen. What do you notice now about the vectors? Explain why this happens.

-The green arrow pushes strong against the direction of the ball and the blue arrow is barely seen as you move at a slow constant speed, but its barely seen coming forth with the green arrow, then moving back the opposite way for a small bit of length before it disappears. Why does this happen? Because velocity is the speed and acceleration is the change of the velocity, explaining why the