Describe 1st class, 2nd class and 3rd class levers:
Answer:
1st = axis between effort force and resistance force, may act with a mechanical advantage or may not (elbow extension, head extension, see saw)
2nd = resistance is between axis and effort arm, mechanical advantage not as versatile as 1st class lever, push up, wheel barrow, calf raise
3rd = Resistance at end, effort force in middle, mechanical disadvantage (knee extension)