Please halp me solve this question!

Aknife blade is a(n) a. lever b. screw c. wedge d. inclined plane

Ablock of mass 1.5 kg slides down an inclined plane that has an angle of 15. if the inclined plane has no friction and the block starts at a height of 3 m, how much kinetic energy does the block have when it reaches the bottom? acceleration due to gravity is g = 9.8 m/s2. a. 6.8 j b. 50.9 j c. 0 j d. 44.1 j

Why is it important always to use horizontal bars in unit fractions when performing unit conversions?