   2d Motion Lab

Pages: 3 (653 words) / Published: Jul 29th, 2013
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.
The vectors appear to have both direct and inverse relationships with each other. When I move the ball one direction, both of the vectors move the same direction i.e. move right, the arrows move right. Then when I exert stopping force onto the ball, the green continues to move with the same direction while the blue moves the opposite direction. The slower I move the ball, the smaller the vectors are and conversely, the faster I move the ball, the larger the vectors are.

2) Which color vector (arrow) represents velocity and which one represents acceleration? How can you tell?
I think the green vector represents velocity while the blue vector represents acceleration. When I slow down the ball movement, the blue vector moves the opposite direction while the green vector continues toward the same direction as the ball. This indicates acceleration increased initially then decreased and velocity continued to increase.

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.
The directions of the vectors are perpendicular to each other. The green vector is longer than the length of the blue vector. The blue vector is accelerating toward the center. The green vector is perpendicular due to being tangent along the path of the circle.

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 vectors are not noticeable. The speed remains constant therefore there would not be acceleration. Velocity