This Interactive is easy to use. The title screen appears upon opening. Tap the Start button to progress to the Main Menu. There are three options on the Main Menu. They are:
  • Put On The Force: investigate situations in which the force is in the direction of the motion.
  • Another Angle On Force:  investigate situations in which the force is in the direction of the motion but at an acute angle to it.
  • Putting On The Brakes:  investigate situations in which the force is in the opposite direction as the motion.
Tapping on any of the options will take you to the simulation window. There is a Control Panel along the top right of the simulation window. The panel includes a back, play|pause forward and reset button. There is also a Help button (question mark) which opens this page. And there is a Home button that takes you back to the Main Menu of three options. Once a simulation is started, it can be paused, backed up one frame, forwarded one frame, or reset to its initial state. A simulation paused part way through can be continued by pressing on the Play button.

A simulation is considered completed if the velocity of the object decreases to 0 m/s (it stops) or if the object reaches the 35-meter mark on the right side of the simulation window. Once a simulation is completed, three new controls are available. There is a KE vs. v Graph button that allows you to view a plot of kinetic energy as a function of speed. There is a View 2-State Bar Chart that allows you to view the energy values as a bar chart in the initial and final state. The work done by the force is also listed in this window. Finally, a scrubber appears below the simulation that includes three buttons on the left and on the right side of the scrubber. These buttons allow you to step through the simulation one frame at a time and view values of the energies, position, speed, and time.  A Reset button is always available once a simulation is completed. 

Values of all variables are listed on the top left of the simulation window. These values can be changed if you tap on the Change Values button. Using the small and large arrows allow you to select a value for the variables force, initial velocity, mass, and coefficient of friction. You also have the additional option of changing the angle of the force on the Another Angle On Force activity. When you tap on the Let's Try It button, a check will be made to determine if the values you have selected will result in an effective simulation. For instance, if your friction is too large such that the object doesn't move, then the program will let you know. And it will give you suggestions for how to remedy the problem. Once acceptable values have been chosen, you will be able to run the trial with those variable values. 
We have provided a Notes page for those who would like to have more information about the concept or the use of the simulation within a physics classroom. If you are struggling with the concepts, then we recommend the Related Resources found on the Notes page. 


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