A runner of mass 50kg can exert a maximum horizontal backward push of 300N on the track without slipping. The coefficient of static friction between shoe and track is 0.60 on a dry day and 0.25 on a wet day. Take g=10ms−2. What is the ratio of the maximum horizontal acceleration possible on the dry track to that on the wet track?
a) 2.0
b) 1.0
c) 2.4
d) 3.0