**Problem Solving Worksheet - In-class problems - Quizzes**

**Applets**

Below are some applets that are available online. I will post the ones I think are good. Almost all of them are either Flash-based or java applets.

**Vector Addition**This applet lets you draw two vectors and it graphically shows how to add them.

**Vector Addition**Another vector adding applet. Grab a vector and you can move it, resize it, and change its direction. You can show the sum of two vectors and the applet will display the component values. This would be a good way to practice - see if you can verify the components calculated by the applet. (note: This applet is from the PhET website. There are MANY other useful applets here)

**Free Body Diagram Practice**In this applet, you create the free body diagram for a given situation. Starting with the "dot" draw the vectors and correctly label them. The applet will check your work. There are more practice problems (they are all excellent). Click on the "Exercises" link at the top of that page, then click on "Force Diagrams" on the side then click on the different examples.

**Friction on an incline**This applet does many things. You can change the angle of incline and it will display the Normal force, the Weight and the Friction vectors.

**Force and Motion**

Here is a java applet from the University of Colorado (http://phet.colorado.edu/simulations/force1d/force1d.jnlp)

When this applet opens, do the following. First, turn off friction. You can do this by unchecking the box on the right hand side of the window.

Now you can click and drag on the file cabinet to apply a force.

What happens when you apply a constant force to this file cabinet (in the unrealistic situation with no friction)?

Once you get the cabinet moving, how do you make it stop?

Now repeat the activity using the refrigerator. What about with the textbook (pushing the textbook that is).

What effect does mass have on this situation?

If you are curious, you can turn friction back on and see what happens.

I may have said this before, but here are some key applets that help with this question: "what does a force do to an object"? This applet is a game called "Maze game". If you really understand what forces do, you should be able to play this. Forces are proportional to the acceleration, so if you click the "acceleration" button you will be all set. Now, the "dot" at the bottom of the screen - if you click and drag a certain direction, this is equivalent to applying a force to the red dot in the game. The goal is to try to get the red dot to the finish location. First level is straight forward. On the upper levels, you must master Newtonian physics to win.

**The Moving Man**

http://phet.colorado.edu/simulations/movingman/movingman.jnlp. If you are having difficulty with position, velocity and acceleration graphs - try this. You can grab the man and make him move, it is fun but not too useful. Instead use the controls on the left to set the velocity or acceleration. Predict what the graphs will be like and then test yourself. Is it possible to have zero velocity, but a non-zero acceleration?

**Friction and Inclined Plane**

http://phet.colorado.edu/simulations/theramp/theramp.jnlp We worked this problem in class, but here you can play with it. Notice that if you apply enough force to get the box moving, it will accelerate. This is because the coefficient of static friction is greater than the coefficient of kinetic friction.

**Rolling Balls and Graphs**

http://www.h7.dion.ne.jp/~jasmin-g/physics/rollball/applet/applet.html. This applet lets you adjust a track that a ball rolls on. It then creates a position-time or velocity-time graph for a ball rolling on that track. If you are having difficulties with graphs, this may help.

**Someone Else's List**

http://www.hal-pc.org/~clement/science.htm. This list may have some overlap with what I have already posted, but it looks useful. I particularly like the "Tools for Scientific Thinking Motion Simulators"