Question

A 6.0 kg mass is placed on a 20° incline which has a coefficient of friction of 0.15. What is the acceleration of the mass down the incline?

Answer 1

$N=mg\cos20°$

$mg\sin20°-\mu mg\cos20°=ma\to a=g\sin20°-\mu g\cos20°=$

$=g\sin20°-\mu g\cos20°=9.8\cdot\sin20°-0.15\cdot9.8\cdot\cos20°=1.97\ (m/s^2)$