Q 01/05

A single fixed pulley changes only what?

A) Load weight

B) Pull direction

C) Rope length

D) Pulling speed

Answer · why

B) Pull direction

Pull direction is all that changes: you haul down on the rope instead of heaving the weight up. Add a second pulley that moves with the weight, and th...

Q 02/05

Which of these is NOT one of the six classical simple machines?

A) Wedge

B) Gear

C) Screw

D) Lever

Answer · why

B) Gear

Gears are combinations of wheels; later engineers such as Franz Reuleaux catalogued hundreds of such "machine elements".

Q 03/05

The ratio of a machine's output force to the force applied is called what?

A) Torque ratio

B) Mechanical efficiency

C) Mechanical advantage

D) Moment of inertia

Answer · why

C) Mechanical advantage

Mechanical advantage need not be above 1. Tools such as tongs score less, giving up force on purpose to gain reach and speed.

Q 04/05

A bicycle is an example of what kind of machine?

A) A perpetual machine

B) An ideal machine

C) A prime mover

D) A compound machine

Answer · why

D) A compound machine

A compound machine links simple ones together, as a bicycle does with wheels, levers and pulleys. In a bench vice the long handle is a lever that turn...

Q 05/05

When several simple machines are linked in series, the overall force multiplication equals what?

A) The product of their ratios

B) The sum of their ratios

C) The average of their ratios

D) The largest single ratio

Answer · why

A) The product of their ratios

The product of their ratios, not the sum: two machines that each triple your force give nine times, not six, when one drives the other.