Module 2: Engineered Products

Brass may be best described as

• an alloy of copper and zinc.

• lamellar composite material.

• mixture consisting of copper and tin.

• a compound of copper and zinc.

Answer explanation

Brass is an alloy of copper and up to 43% zinc.

Force systems consisting only of forces that intersect

at a common point are known as

• co-planar.

• co-linear.

• concurrent.

• codependent.

Answer explanation

Concurrent force systems incorporate forces whose lines of action all intersect at a common point but may lie on different planes.

Resultants and equilibrants are

• identical.

• the same except for sense.

• the same except for magnitude.

• the same except for direction.

Answer explanation

An equilibrant is identical to the resultant in magnitude and direction but is opposite in sense.

Work hardening most often results in

• an increase in strength with a decrease in ductility

  and hardness.

• an increase in hardness with a decrease in ductility

  and strength.

• an increase in ductility and hardness with a decrease

  in strength.

• an increase in hardness and strength with a decrease

  in ductility.

Answer explanation

Work hardening is a result of plastic or permanent deformation of the crystal structure that increases hardness and strength but reduces ductility.

Alloys produced from metals of similar atomic size

form structures known as

• interstitial.

• substantial.

• intermetallic.

• substitutional.

Answer explanation

Substitutional alloys form when the atomic radius of the alloying (solute) element differs by no more than 15% from that of the base (solvent) metal. Intermetallics are compounds and interstitional alloys occur when atomic radii differences are large.

Grey cast iron's strength comes from

• the casting process

• the homogeneity of its structure.

• high concentrations of martensite.

• its metallic matrix in which graphite is distributed

Answer explanation

Grey cast iron does not have a homogeneous structure nor does it contain martensite. The casting process does not add any strength but its largely metallic matrix does improve strength.

The direction of the force exerted on a moving

charge by a magnetic field may be determined by

• the rule of force.

• the left-hand rule

• the right-hand rule

• the three force rule.

Answer explanation

The three force rule refers to vectors.

The left hand rule deals with charged particles entering a magnetic field. The right hand rule is used to determine the direction of the force felt by a charge moving with velocity through magnetic field.

Magnetic fields are produced by

• stationary charges

• stationary or moving charges

• moving electric charges measured in teslas

• moving electric charges measured in faradays

Answer explanation

Moving electric charges create magnetic fields that are measured in teslas.

The absence of what leads to greater longevity of

induction motors.

• astator

• brushes

• windings

• moving parts

Answer explanation

The absence of brushes that would normally wear out lead to low maintenance and an extended lifetime for induction motors.

Induction cooktops rely on

• the creation of a magnetic field.

• induced current in the pan base

• direct contact between the cooktop and pan.

• heat transferred from the cooktop to the pan.

Answer explanation

Electromagnetic induction cooktops rely on the creation of a magnetic field, which induces a current in the base of a ferrous metal pot placed on the cooktop surface. the cooktop itself remains cool. Just placing a pot in contact with a cooktop surface does not produce any heat.