Block M slides down the shown frictionless 37° incline. The minimum friction coefficient required so that block m does not slide relative to M is n/4. Find n.

Question

G1 Physics · Accepted Answer

For the upper block to remain fixed relative to M, friction must balance the component of the effective force parallel to the contact surface. Using the acceleration of M down the 37° incline and resolving the effective gravity gives μₘᵢₙ = 3 4 \frac{3}{4} 4 3 ​ . Therefore n = 3.