An object, previously at rest, slides 9 m9m down a ramp, with an incline of (pi)/6 π6, and then slides horizontally on the floor for another 24 m24m. If the ramp and floor are made of the same material, what is the material's kinetic friction coefficient?

1 Answer
Feb 20, 2016

k~=0,142k0,142

Explanation:

pi/6=30^oπ6=30o
E_p=m*g*h " Potential Energy of Object"Ep=mgh Potential Energy of Object
W_1=k*m*g*cos 30*9 W1=kmgcos309
"Lost energy because friction on inclined plane"Lost energy because friction on inclined plane
E_p-W_1": energy when object on ground"EpW1: energy when object on ground
E_p_W_1=m*g*h-k*m*g*cos 30^o*9Ep_W1=mghkmgcos30o9
W_2=k*m*g*24 " lost energy on the floor"W2=kmg24 lost energy on the floor
k*cancel(m*g)*24=cancel(m*g)*h-k*cancel(m*g)*cos 30^o*9
24*k=h-9*k*cos 30^o
"using "cos 30^o=0,866 ;h=9*sin30=4,5 m
24*k=4,5-9*k*0,866
24*k+7,794*k=4,5
31,794*k=4,5
k=(4,5)/(31,794)
k~=0,142