Question

A particle moves on the rough horizontal ground with some initial velocity say v. If 3/4th of its kinetic energy is lost in friction in time t then coefficient of friction between the particle and the ground is:

• A. v/2gt
• B. v/4gt
• C. 3v/4gt
• D. v/gt

Answer 1

The correct option is A v/2gt

Initial velocity=$v$

As 3/4 th kinetic energy lost so 1/4 kinetic energy remain after time 't'

So velocity after time 't'= $v/2$

retardation due to friction=$-\mu g$

apply first equation of motion

$v=u+at$

$v/2=v-\mu gt$

$\mu =v/2gt$