1. A block of mass 57.1 kg rests on a slope having an angle of elevation of 28.3°. If pushing downhill on the block with a force just exceeding 162 N and parallel to the slope is sufficient to cause the block to start moving, find the coefficient of static friction.
HINT - Draw the block's free-body diagram and apply Newton's second law for the tilted x-component, solving for μs after substituting
fs, max = μsn.
2. A dockworker loading crates on a ship finds that a 25-kg crate, initially at rest on a horizontal surface, requires a 70-N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 54 N is required to keep it moving with a constant speed. Find the coefficients of static and kinetic friction between crate and floor.
static friction - ???
kinetic friction - ???