Medium
In a lever the effort arm is 60 cm and the load arm is 20 cm. What effort is needed to lift a load of 90 N?
Explanation
Explanation
Step 1: The principle of a lever (in balance): Effort × Effort arm = Load × Load arm.
Step 2: Substitute: E × 60 = 90 × 20.
Step 3: E = 1800 ÷ 60 = 30 N.
Step 4: Check using mechanical advantage: MA = effort arm ÷ load arm = 60 ÷ 20 = 3, and load ÷ effort = 90 ÷ 30 = 3 ✓.
Answer: 30 N.
PRO TIP
Re-check your working by substituting the answer back into the original question.