Answer to Question #97196 in Mechanics | Relativity for Ojugbele Daniel

Question

A box of mass 4.5kg is pull at a constant speed of 2m/s along a rough horizontal floor by a horizontal force of magnitude 15N.
(i) find the coefficient of friction between the box and the floor. The horizontal pulling force is now removed. Find:
(ii) the acceleration of the box in the subsequent motion.

Answer 1

(i) Since the speed is constant, sum of the force of the friction and pulling force is 0.

So, $15=k*4.5*9.8$ .

Then, $k=\frac{15}{4.5*9.8}=0.34.$

(ii) $f=ma,\;\;a=\frac{f}{m}=\frac{-15}{4.5}=-3.33\; m*s^{-2}$