OAR OAR Mechanical Comprehension: Simple Machines Questions and Answers 3

Question 1

Which class of lever has the effort applied between the fulcrum and the load?

Accepted Answer

Third class

Answer

In a third-class lever, the effort is applied between the fulcrum and the load, which increases speed and range of motion at the cost of force.

Question 2

A mechanic uses a 12-inch wrench to turn a bolt with an effective radius of 0.5 inches. What is the ideal mechanical advantage?

Accepted Answer

24

Answer

The wrench acts as a wheel and axle, so mechanical advantage = effort radius / load radius = 12/0.5 = 24.

Question 3

An inclined plane reduces the force needed to raise an object by increasing which of the following?

Accepted Answer

The distance over which the force is applied

Answer

An inclined plane trades increased distance for reduced force, keeping the total work the same.

Question 4

A fixed pulley is attached to the ceiling to lift a load. What is the primary advantage of this single fixed pulley?

Accepted Answer

It changes the direction of the applied force

Answer

A single fixed pulley provides a mechanical advantage of only 1 but allows the user to pull downward instead of lifting upward.

Question 5

A knife blade is an example of which simple machine?

Accepted Answer

Wedge

Answer

A knife blade is a wedge that converts the downward cutting force into two forces that push the material apart.

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