OAR OAR Mechanical Comprehension: Simple Machines Questions and Answers 2

Question 1

A worker uses a wheel and axle to lift a bucket from a well. If the wheel has a radius of 30 cm and the axle has a radius of 5 cm, what is the mechanical advantage of this system?

Accepted Answer

6

Answer

The mechanical advantage of a wheel and axle equals the wheel radius divided by the axle radius: 30/5 = 6.

Question 2

Which simple machine is represented by a doorstop being pushed under a door?

Accepted Answer

Wedge

Answer

A doorstop is a wedge, which converts force applied to its blunt end into forces perpendicular to its inclined surfaces.

Question 3

A screw has 8 threads per inch. What is the pitch of this screw?

Accepted Answer

1/8 inch

Answer

Pitch is the distance between adjacent threads, calculated as 1 divided by the number of threads per inch: 1/8 inch.

Question 4

A 200-lb crate is pushed up a 10-foot ramp to a loading dock 4 feet high. Ignoring friction, how much force is required to push the crate up the ramp?

Accepted Answer

80 lb

Answer

The ideal mechanical advantage of an inclined plane is length/height (10/4 = 2.5), so the required force is 200/2.5 = 80 lb.

Question 5

In a compound pulley system with 4 supporting ropes, how much effort is ideally needed to lift a 240-lb load?

Accepted Answer

60 lb

Answer

In an ideal compound pulley, the effort equals the load divided by the number of supporting ropes: 240/4 = 60 lb.

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OAR OAR Mechanical Comprehension: Simple Machines Questions and Answers 2