Hi Candidate,

The free fall distance is s which is experiencing a force of F equal to the mass of without the body, any external force in a certain time.

Now as we have a frictional force of F/2, equals to half of the weight in the same certain time, so as Force is directly proportional to distance, hence the value of distance also get halved as the force gets halved.

Hope that you have got your answer. All The Best. Have a Good Day!!