A 2kg block rests on a rough incline at 20∘ to the horizontal (tan20∘=0.364). The coefficient of static friction is 0.40. A student gently pushes the block with a 5N force directed up the slope, but the block remains at rest. Which one of the following best describes the static friction acting on the block? (Take g=9.8m s−2.)
a) Down the slope, about 1.7N
b) Up the slope, about 6.7N
c) Up the slope, about 1.7N
d) Up the slope, about 7.4N