Final answer:
The force needed to lift an object using a lever varies inversely as the length of the lever. Using this relationship and the given information, we can find the force needed for a 36-inch long lever.
Step-by-step explanation:
According to the given information, the force needed to lift an object using a lever varies inversely as the length of the lever. So, we can set up an equation:
F ∝ 1/l
Using the values given, we can solve for the constant of variation:
F = k/l
240 = k/24
Solving for k, we get k = 5760
Now, we can use this constant to find the force needed for the 36-inch long lever:
F = 5760/36
= 160 pounds