In the first method you will determine the coefficient of static friction between a wooden block and a horizontal surface. The block is connected to a string which hangs over a pulley and is connected to a mass hanger.
Find the mass of the block with the triple beam balance. Add weights to the hanger in small increments until the block breaks free and starts to move. Record the total hanger mass.
Place the .2 kg weight on top of the block and repeat the procedure above. Be sure to place the block at the same point each time. Repeat with the .5 and 1.0 kg weights on top of the block.
Draw a free body diagram and derive an expression for ms in terms of the hanger mass and the total masss of the block. Using this expression, calculate ms for all four trials. Find the average and estimate the error in the value of the coefficient from the range of values.
Place the block on the surface and slowly raise the end. Using a protractor, find the angle at which the block breaks free and slides down the inclined plane. Record this angle and repeat the procedure three more times, making certain that you place the block at exactly same point each time. Place the flat weight on the block and repeat the experiment.
Draw a free body diagram of the block and derive an expression for ms as a function of the angle (q) of incline of the surface. Using the average angle of all four trials, calculate ms for the block alone and again for the block with the weight. Estimate the error for each case as was done in part A.
