Question

A 15-kg sled is being pulled along the horizontal snow-covered ground by a horizontal force of 23 n. starting from rest, the sled attains a speed of 1.8 m/s in 8.5 m. find the coefficient of kinetic friction between the runners of the sled and the snow.

Answer 1

We know the relationship between distance traveled and velocity obtained under acceleration a:
$a=\frac{v^2}{2S}=\frac{1.8^2}{2\cdot8.5}=0.19\frac{m}{s^2}$
We know from second Newtons law that net force acting on the object is proportional to its mass and acceleration:
$F_n=ma$
The net force acting on the sledge is:
$F_p-F_f=ma\\ F_f=F_p-ma\\ \mu mg=F_p-ma\\ \mu=\frac{F_p-ma}{mg}\\ \mu=\frac{23-15\cdot0.19}{15\cdot 9.81}=0.14$