A lever is used to lift a heavy weight. The length of the input arm of the lever is 3 m, the length of output arm is 1 m. What is the mechanical advantage of the lever?

3
1
4
0.33

a and b sometimes have a positive value

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle

it's a b and