Answer:
F = 5226.6 N
Explanation:
To solve a lever, the rotational equilibrium relation must be used.
We place the reference system on the fulcrum (pivot point) and assume that the positive direction is counterclockwise
F d₁ = W d₂
where F is the applied force, W is the weight to be lifted, d₁ and d₂ are the distances from the fulcrum.
In this case the length of the lever is L = 5m, t the distance desired by the fulcrum from the weight to be lifted is
d₂ = 200 cm = 2 m
therefore the distance to the applied force is
d₁ = L -d₂
d₁ = 5 -2
d₁= 3m
we clear from the equation
F = W d₂ / d₁
W = m g
F = m g d₂ / d₁
we calculate
F = 800 9.8 2/3
F = 5226.6 N
