OAR OAR Mechanical Comprehension: Simple Machines 4

Question 1

A second-class lever always has a mechanical advantage:

Accepted Answer

Greater than 1

Answer

In a second-class lever the load is between the fulcrum and the effort, so the effort arm is always longer, giving MA > 1.

Question 2

Two interlocking gears: Gear 1 has 20 teeth and Gear 2 has 5 teeth. If Gear 1 is the driver, the gear ratio is:

Accepted Answer

0.25

Answer

Gear ratio (output/input) = teeth on driven gear / teeth on driver = 5/20 = 0.25, meaning the output spins faster.

Question 3

Work input always equals work output in an ideal simple machine because:

Accepted Answer

Energy is conserved

Answer

In an ideal (frictionless) machine, the law of conservation of energy ensures work in equals work out.

Question 4

A flagpole uses a pulley to raise a flag. This is an example of which pulley type?

Accepted Answer

Fixed pulley

Answer

A flagpole uses a fixed pulley, which changes the direction of force but provides no mechanical advantage.

Question 5

If the efficiency of a machine is 80% and the work input is 500 J, what is the useful work output?

Accepted Answer

400 J

Answer

Useful work output = efficiency × work input = 0.80 × 500 = 400 J.

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