What does mechanical advantage describe regarding simple machines?

they multiply the input force.

they are manufactured.

they change the total amount of work that is done.

They multiply the input force.

Explanation:

Mechanical Advantage is the multiplication of the input force to give an increased output by a simple machine due to the difference in the length of load arm and the effort arm.

It is based upon the law of conservation of moments as to force applied at the farther point from a hinge or a pivot needs to be balanced by a greater force counteracting at a shorter distance from the pivot.

Lever is a simple machine which consists of a bar pivoted or supported at a point (called fulcrum) about which it can rotate.

..............................................(1)

where:

force applied on the end of effort arm

force due to load on the end of load arm

L = length of load arm

E = length of effort arm

Equation (1) is known as the law of levers, it was proven by Archimedes using geometric reasoning.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27