Question

What load could be lifted by a 5 m long lever with a fulcrum 2m from the load if the effort is 30 N?

75 N
12 N
45 N
20 N

Answer 1

The answer is 45N Ive this problem before

Answer 2

F₁ = effort applied = 30 N

F₂ = load applied = ?

r₁ = distance of effort force from the fulcrum = ?

r₂ = distance of load force from the fulcrum = 2 m

L = length of the lever = 5 m

from the diagram , we see that

L = r₁ + r₂

inserting the values

5 m = r₁ + 2 m

r₁ = 5 m - 2 m

r₁ = 3 m

using equilibrium of torque about the fulcrum from the diagram

F₁ r₁ = F₂ r₂

inserting the values

(30) (3) = F₂ (2)

F₂ = 90/2

F₂ = 45 N

hence the correct choice is 45 N