Period+2+Exploring+Friction+Group+4

Together with your group, come up with a name for your group in the spirit of our physics unit! Fun Frictionz Zach H. and William R.
 * Exploring Friction **
 * Our Group Name:**


 * Work through this lab as a group. Try to encourage everyone to be involved, have a voice, and use their skills!**

What is the definition of friction? Resistance that one surface/object when moving over another

Define these two types of friction: Static Friction – Must be overcome before an object moves, greater than sliding friction

Sliding Friction – friction between two objects in sliding contact

Use the blocks, masses, and spring scale to make observations on the amount of force needed to get a mass moving and the amount of force needed to keep the mass moving. Write down your observations.


 * Observations:**

Spring scales measure force. Weight is the force on an object due to gravity but a spring scale can also measure the force needed to pull an object. If the spring scale reads 100 g it means that the force is about 1 N. If the spring scale reads 200 g it means that the force is about 2 N.
 * About the spring scale –**

A triple beam balance measures mass in grams. Since w=mg where w is weight in N, m is mass in kg, and g is 9.8 (acceleration due to gravity) then we can convert the mass on our balance to weight using the formula below. Weight (N) = Mass (kg) X 9.8 or Weight (N) = Mass (g) X 0.0098
 * About the triple beam balance –**

1. Experiment by pulling the block with the hook using the spring scale. Lay the block down on the table so that the largest surface is in contact with the table. Try applying such a small force that the block doesn’t move. What did the scale read when the block just begins to move? __g =__ N //This number represents the force of static friction between the block and the table.//
 * Conduct an Experiment**

2. Continue pulling the block across the table at a steady speed. What did the scale read as you pulled the block at a steady speed? __g =__ N //This number represents the force of sliding friction between the block and the table.//

3. Create a data table to record the forces of static and sliding friction as you increase the mass of the blocks/objects you pull across the table. Be sure to convert the mass to weight using the formula above. Create another row for each set of blocks you pull.
 * < Objects || Mass (g) || Weight (N) || Static Friction (N) || Sliding Friction (N) ||
 * < Block 1 || 155 || 1.5 || 0.2 || 0.1 ||
 * < Block 1 + 2 || 287.2 || 2.8 || 0.8 || 0.2 ||
 * < Block 1 + 2 + 3 || 437.7 || 4.2 || 1.1 || 0.8 ||
 * < Block 1 + 2 + 3 + 4 || 576 || 5.6 || 1.3 || 1.1 ||
 * < Block 1 + 2 + 3 + 4 + 5 || 682.5 || 6.6 || 2.0 || 1.2 ||

4. Stop and analyze the data in your table. Describe the relationship between the weight of the objects you pulled and each type of friction. What is the pattern seen in the table?

__With more blocks, the friction increases - The sliding friction is always less than the static friction__

5. Create a graph to show the relationship.
 * Identify the independent variable for the x- axis:
 * Identify the dependent variable for the y-axis:
 * What type of graph is appropriate for this set of data?
 * What can be done to distinguish the static friction data set from the sliding friction data set?
 * Create the graph using “Create a Graph” or paper and pencil.

6. Stop and analyze the graph of your data. Describe the correlation between the weight of the objects you pulled and each type of friction. How is the correlation shown in the graph?



__As the weight goes up, the friction goes up. The graph shows a strong positive correlation. The sliding friction is still lower than the static friction.__

Choose a question from below or develop your own unique question with your lab group. Design and conduct an experiment to help find the answer to the question. Complete an experimental design diagram and have it approved before beginning. __Experimental Design Diagram__ __Question:__ How will the static and sliding friction of the blocks change when sliding across the bumpy surface __Hypothesis:__ There will be greater friction because the surface is bumpier and, therefore, will catch on the blocks more. __Independent Variable:__ Weight of blocks (N)
 * Your Turn**
 * 1) How would the amount of static and sliding friction change if the bottom block was placed so the smaller surface was in contact with the table?
 * 2) ** How would the amount of static and sliding friction change if the blocks were placed on a different surface? **
 * Levels of the IV: || (Control)  Block 1 || Block 1+2 || Block 1+2+3 || Block 1+2+3+4 || Block 1+2+3+4+5 ||
 * Repeated Trials: || 1 || 1 || 1 || 1 || 1 ||

__Dependent Variable:__ Friction (N) __Constants:__ Blocks, scale __Procedure:__ 1. Drag 1st block across surface 2. Measure friction and record 3. Add 2nd block 4. Measure an record 5. Continue to add blocks and measure __Data Table:__
 * Block || Static Friction (N) || Sliding Friction (N) ||
 * 1 || 0.1 || 0.05 ||
 * 1+2 || 0.8 || 0.2 ||
 * 1+2+3 || 1.2 || 0.3 ||
 * 1+2+3+4 || 2 || 0.8 ||
 * 1+2+3+4+5 || 2.1 || 1.1 ||

__Graph:__ In this graph, the static friction stayed about the same but the sliding friction went down.

__Video:__ media type="custom" key="26182306"