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Static and Kinetic Friction Force

AIM                                                                                                                           To determine the relationship between the normal force and the maximum static and kinetic friction respectively, experienced by an object.

HOW DOES IT WORK?                                                       

    Time allocation: 45 Min

Learners determine the mass of each weight and calculate the normal force. This is the force equal to the gravitational force but in the opposite direction. The spring balance is attached to the hook of the weight and pulled horizontally until the block just starts moving. The reading on the balance is noted. They also determine the force needed to pull the same weight at a constant velocity across the surface.

The graphs obtained from the results prove that the maximum static friction as well as kinetic friction is directly proportional to the normal force. The gradient of the straight line graphs are constant and represent the coefficient of static friction and the coefficient of kinetic friction.

Derived from the following formula:
μu=FG

 

F= μMg

 

fg=μM

MATERIALS:

The box includes:

  • Hexagonal Weights 100g, 200g, 500g
  • Force meter Tubular balance

METHOD

  1. Find an even Horizontal work surface.
  2. Learners determine the mass of each weight and calculate the normal force. The normal force is the force equal to the gravitational force but in the opposite direction.
  3. The spring balance is attached to the hook of the weight and pulled horizontally until the block just starts moving. The reading on the balance is recorded in the table as maximum static friction.
  4. The learners pull the weight at a constant velocity across the surface. Record the force needed to pull the block at a constant velocity (this is one motion as opposed to snatching the block, if the block is snatched it will be considered acceleration as the speed would differ from the initial velocity to the duration of its final rest) as maximum kinetic friction.
  5. Repeat step 1- 4 and record the readings in a table use the following headings: mass of weight, normal force, maximum static friction, and maximum kinetic friction. The results are represented in a graph to determine the relationship between the normal force and max static and kinetic friction