Problem 1

A block is released from rest on a plane inclined at

\theta=30^\circ

. The kinetic-friction coefficient is

\mu_k=0.20

and

g=9.8\,\mathrm{m/s^2}

. Contact is maintained and friction opposes sliding; take the positive axis down the plane. (a) Find the first requested quantity. (b) Find the second quantity. (c) Determine the final result and check its units. (a) Find the normal reaction. (b) Find the kinetic-friction force. (c) Find the acceleration and determine its direction.

problems.proof.stepOf

problems.proof.prevStep problems.proof.nextStep

N=mg\cos\theta

problems.proof.analysis

First identify the physical model and convention that match the stated setup. This fixes the signs used in the equations that follow.