Question

For this problem you will need measurements of the position vs. time of a block sliding on a table, starting with some initial velocity, showing down, and coming to rest. If you do not have an appropriate laboratory setup for making these measurements, your instructor will provide you with such data. Analyze these data to determine the coefficient of friction and to see how well they support the assertion that the force of sliding friction is essentially independent of the speed of sliding.

Short answer

The coefficient of friction is determined by using a position vs. time graph which is essentially independent of the speed of sliding.

Step-by-step solution

Significance of coefficient of friction

• The force needs to resist the movement of an objectis known asfrictional force

• The parameter gotten from theposition vs time graph is velocity. If theslope is deeper, thenquicker the movement is changing.

• The ratio of friction force to normal force is defined as the coefficient of friction

• The coefficient of kinetic friction is defined asthe ratio of kinetic friction force to the normal force.

• The coefficient of kinetic friction is defined asthe ratio of static friction force to the normal force.

• The coefficient of static friction is known as the limiting friction which has the maximum value.

• The coefficient of kinetic friction has the magnitude of the constant force which has less than the limiting friction.
  
  
• The coefficient of static frictionis equal to or greater than the coefficient of kinetic friction.

Determination of coefficient of friction using position vs. time

• We have to set up an experiment for a block sliding on a table to measure the force of friction.
• We have to start with some initial velocity, showing down, and coming to rest to measure a moving distance L
• We have to draw the friction force F , on the y - axis , and Normal Force N on the x - axis .
• The slope of that graph will indicate the coefficient of kinetic friction.
• We have to find the + y component perpendicular to the slope and + x down the slope by using a coordinate system.
• Then apply Newton’s second law.
• The tangent of the angle where the object slides, is knowns as the coefficient of static friction.
• Sliding friction does not have the same variables, so it is independent of the speed of the sliding.
• Sliding friction depends upon the material and the weight of the object.

Hence, using the above method the coefficient of friction is determined by using a position vs. time graph which is essentially independent of the speed of sliding.