Question

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.

Answer 1

When the tension is T = 16 N

The frictional force is
`F_F = 22.2 \ N`

When the tension is T = 38 N

The frictional force is
`F_F = 11.1 \ N`

Step-by-step explanation:

From the question we are told that

The weight of the block is
`w = 35 \ N`

The coefficient of static friction is
`\mu_s = 0.6`

The coefficient of kinetic friction is
`\mu_k = 0.3`

considering when the tension is T = 16 N

`W > T` This implies that that block will not slide

Hence the frictional force is mathematically evaluated as

`F_F = \mu_s * W`

=>
`F_F = 0.6 * 37`

=>
`F_F = 22.2 \ N`

considering when the tension is T = 38 N

`W < T` This implies that that block will start sliding

Hence the frictional force is mathematically evaluated as

`F_F = \mu_k * W`

=>
`F_F = 0.3 * 37`

=>
`F_F = 11.1 \ N`