Question

If reaction is \(R\) and coefficient of friction is \(\mu\), what is the work done against friction in moving a body by distance \(d\)?

• A. \(\mu R d\)
• B. \(\frac{\mu R d}{2}\)
• C. \(2 \mu R d\)
• D. \(\frac{\mu R d}{4}\)

Hint:

The work done against friction is the product of the frictional force and the distance move(D) The frictional force is calculated as \(F = \mu R\), where \(\mu\) is the coefficient of friction and \(R\) is the normal reaction force.

Answer 1

The Correct Option is A

The work done \(W\) against friction is given by the formula: \[ W = F \times d \] Where: - \(F\) is the frictional force, - \(d\) is the displacement. The frictional force \(F\) is given by the relation: \[ F = \mu \times R \] Where: - \(\mu\) is the coefficient of friction, - \(R\) is the reaction force (which is equal to the weight of the body if it is moving horizontally on a flat surface). Thus, the work done against friction is: \[ W = \mu R \times d \] Hence, the work done is \(\mu R d\).