A worker lifts a stone with a mass of m = 120 kg using a scrap, applying F = 100 N to the free end of the scrap

A worker lifts a stone with a mass of m = 120 kg using a scrap, applying F = 100 N to the free end of the scrap. What is the length of the scrap if the distance from its end to the point of contact between the scrap and the stone is l1 = 10 cm? The coefficient g should be taken equal to 10 N / kg. Do not take into account the mass of scrap and the size of the stone.

Let us give the values from given in the SI system:
l2 = 10 cm = 0.1 m.
According to the rule of leverage: the gain in force obtained with the help of the lever is determined by the ratio of the arms of the applied forces. Let’s express it with the formula:
F2 / F1 = l1 / l2
In our case, F1 is the force applied to the scrap, F2 is the body weight.
Determine the body weight:
F2 = m * g = 120 * 10 = 1200 N
Let us express the length of the larger arm from the lever equation:
l1 = F2 * l2 / F1
Substitute the numerical values:
l1 = F2 * l2 / F1 = 1200 * 0.1 / 100 = 1.2 m
Now let’s find the length of the scrap:
l = l1 + l2 = 1.2 + 0.1 = 1.3 m.
Answer: the length of the scrap is 1.3 m.