Answer to Question #181430 in Classical Mechanics for Martins

Question

A body of mass 25kg, moving at 3m/s on a rough horizontal floor is brought to rest after sliding through a distance of 2.5m on the floor. What is the coefficient of sliding friction (g=10)

Answer 1

Answer

Using v=u+at

a = $\frac{3}{t}$

Using s=ut+$0.5at^2$

$d = 0.5a t^2$

$2.5 =0 .5\times\frac{ 3}{t}t^2$

2.5 = 1.5 t

t = 1.67 seconds to stop

then$a = \frac{3}{t }= 1.8 m/s^2$

F = ma

F = 25 $\times$ 1.8 = 45 N

weight = 25g = 250N

coef of friction $=\frac{ F}{weight} = \frac{45}{250} = 0.18$