please give me analysis problem answer! thanks Review Questions I. Explain what
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please give me analysis problem answer! thanks
Review Questions I. Explain what is meant by the term "coefficient of static friction." 2. tow does the coficient of static fiection differ from the coficien ofkinetic riction? 3. Show why the friction force is equal to the weight of the hanging mass. 4. Why is the coefficient of static fric 5. A force of 2 N pulls a I kg block at a constant velocity. Calculate the coefficient of kinetic tion greater than the coefficient of kinetic friction? friction for the surfaces in contact Procedure 1. Wipe all faces of the wooden block and determine its mass. Also wipe the board. 2. Set up the apparatus as shown in Figure 4, making sure that the wooden board is perfecetly 3. Adjust the weights on the weight hanger and tap the board slightly, so that the block slides level. Place the block with one of its larger faces in contact with the board. across the board with a uniform (constant) velocity. You may wish to observe the block s constant velocity in a certain area of the board rather than across the whole board. Also, it is usually not necessary to use weights lower than 5 grams on the weight hanger 4. Place 200, 400, 600, 800 grams successively on the block and repeat step 3 5. 1401: Place the block on its side, place 200 g on it, and repeat step 3. 2425: Place the block on its side and repeat steps 3 and 4 6. Place the block flat on the board, put some weights on it, and determine the mass needed on the weight hanger when the block just begins to move. Since this is to determine the coefficient of static friction, do not tap the board. Record the results in Table 2. in the region where you did most of your experiment. angle of the inclined plane until the block just begins to slide. Repeat this procedure at 7. Remove the string and weight hanger from the block, and place the block flat on the board, 8. Lift up one end of the board so that it becomes an inclined plane. Keep increasing the least thrice and record the angle of repose in Table 3 9. Place the rough board on the inclined plane and determine the angle of repose 10. Use the data of Table 1I to plot a graph between the normal force N (along x-axis) and the kinetic friction force f (along y-axis). Check with your Instructor if you can do this on the computer. Instructions for drawing graphs with the computer are in the Introduction. Find the slope of the graph. This represents 11 . I 401 : Use equation 3 to determine when the block lay on its side and calculate the % 12. 2425: Draw another graph using the data when the block was on its side. Determine us for 13. Use Equation 2 to determine using data Table 2, and Equation 7 to determine for the difference for your two values of py this arrangement of the block and calculate the % difference. different surfaces in data Table 3, Calculate the % difference for your 2 values ofu Equation 7 to determine us for the 67Explanation / Answer
1) Here, coefficient of static friction s is determined more precisely . coefficient of kinetic friction k is determined more accurately . This is because many values of coefficient of static friction s are taken and the % difference between them is calculated . While coefficient of kinetic friction k is measured with the proximity of its true value .
2) If the string is not parallel, the tension in it will be at an angle, which will alter results. It needs to pull directly along the "wooden plane". The horizontal part of equation will contain Tcos(theta) and vertical part will contain Tsin(theta) .
the friction will change, because if not parallel, either an up or down component would be added to or subtracted from the normal force.
If up, the friction would be less, and if down, friction would be greater.
3) Sources of Error
a) may have been accelerating the box, rather than applying a force only sufficient to overcome friction.
b) Lack of small incremental weights. We had to use larger weights .
c) the contribution of friction by the pulley and the string.
d) String may not be parallel to the plane .
4) a) Frictional Force = s N
b) s >= k. The coefficient of static friction is typically larger than the coefficient of kinetic friction. It is the threshold of motion which is characterized by the coefficient of static friction.
c) The frictional force or coefficient of friction is independent of area of contact .
d) The frictional force or coefficient of friction is dependent on nature of surfaces in contact .Rougher surfaces have higher coefficient of frictions but to slide apart.
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