A 35 N block rests on a horizontal surface. The coefficients of static and kinetic friction between the surface and the block are 0.6 and 0.3, respectively. A horizontal string is attached to the block and a constant tension is maintained in the string. What is the force of friction acting on the block if the tension is 16 N? Answer in units of N. What is the force of friction acting on the block if the tension is 38 N? Answer in units of N.

When the tension is  T =  16 N  

  The frictional force is  

When the tension is  T =  38 N  

    The frictional  force is        

Explanation:

From the question we are told that

   The weight of the block is  

    The coefficient of static friction is

     The coefficient of kinetic friction is  

considering when the tension is  T =  16 N  

          This implies that that block will not slide

Hence the frictional  force is  mathematically evaluated as

=>      

=>              

considering when the tension is  T =  38 N  

    This implies that that block will start sliding

Hence the frictional  force is  mathematically evaluated as

=>      

=>              

an electric circuit