A car starts rolling down a 1-in-8 hill (1-in-8 means that for each 8 m traveled along the road, the elevation change is 1 m).

Question

A car starts rolling down a 1-in-8  hill (1-in-8  means that for each 8 m traveled along the road, the elevation change is 1 m).
 A) How fast is it going when it reaches the bottom after traveling 90 m ? Assume an effective coefficient of friction equal to 0.10.

bobpursley · Answer

on the slope, sinTheta=1/8

friction=.1*mg*cosTheta (figure out cosTheta from the sine)

force down the slope=mg*sinTheta

net force=mg*sinTheta-.1mg*cosTheta
net acceleation=force/mass= you do it.

vf^2=2*netAcceleration*distance