Physic Labs

Problem 1

A block is released from rest on a plane inclined at θ=30∘\theta=30^\circ. The kinetic-friction coefficient is μk=0.20\mu_k=0.20 and g=9.8 m/s2g=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.
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a>0⇒block accelerates downhilla>0\Rightarrow\text{block accelerates downhill}
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Finally substitute the given values and check units and limiting behavior. The result agrees with the signs and scale implied by the model and previous parts.