Position, Velocity & Acceleration
· To study position (x), velocity (v) and acceleration (a)
· Solve simple one-dimensional motion problems involving the concepts of constant velocity and constant acceleration
· Draw graphs representing various motions
1. On your computer, open the browser and go to – https://phet.colorado.edu/en/simulation/moving-man
2. Click on the “Run Now” button, located just below the picture at the center of the page. That should open up a new window that looks like this
3. If the new window fails to launch, try the “Download” button right next to “Run Now”. Once downloaded, you can double-click on the file to start the simulation. If the simulation still does not run, you most likely need to install “java” in your computer, which you can do for free from the java website – https://www.java.com/en/
4. Once the simulation is running and you come to the screen shown in the picture above, you can see the picture of a man, standing at the origin (0 meter mark). Change the velocity to 1 m/s (you can slide the velocity adjustor or simply write “1” in the box. Hit the “Play”/”Start” button (the blue button with the black arrow at the bottom of the screen). You can see the man walking to the right at a constant speed of 1 m/s, until he hits the wall. If you want, you can review the motion again by first clicking the “Pause” button (same blue button), then checking “Playback” and clicking “Play” again. That will repeat the motion as it happened.
5. Click the “Reset All” button at the bottom right corner and then click “yes”. Change the velocity to -1 m/s and hit play. This time, the man walks at a steady speed of 1 m/s to the left.
6. Click the “Reset All” and then click “yes”. Now change the acceleration to 1 m/s2 and hit “Play”. What did you see? The man starts from rest but speeds up as he walks to the right.
7. How long would it take for him to walk the 10 m? Solve for the time using the constant-acceleration motion equations show the calculation:
Time taken to walk 10 m _____________ (from calculation)
Now, repeat step 6 to find out the time from the simulation. You will need to hit the pause button as the man approaches the 10 m mark, to find the time.
Time taken to walk 10 m _____________ (from simulation)
8. Click the “Reset All” and then click “yes”. Now change the acceleration to -1 m/s2 and hit “Play”. What did you see? The man starts from rest but speeds up as he walks to the left.
9. Click the “Reset All” and then click “yes”. Now change the velocity to 6 m/s and acceleration to -2 m/s2. DO NOT hit “Play” yet. What do you think will happen? Try to write a brief answer BEFORE watching the actual motion.
What will happen?
10. Now hit “Play”. Did you answer correctly? Write down the answer.
11. Click on the “Charts” tab located at the top left corner – next to the “introduction” tab. Hit “Reset All” at the bottom.
Change the velocity to 2 m/s and hit “Play”. The graphs that appear nicely show that the position is steadily increasing with time, velocity is constant and acceleration is 0.
12. Reset. Change the position to -10 m, keep velocity to 0 m/s, and change acceleration to 5 m/s2. Hit play. Again, you can see that graphs show that position vs time is an upward curve, velocity vs time is a steadily increasing line and acceleration vs time is a flat line (constant).
13. Take a look at the picture below. This picture shows the recorded position, velocity and acceleration versus time graphs, at the end of the motion.
Can you guess how the motion started?
Initial position __________
Initial velocity __________