ASVAB Mechanical Comprehension Practice Test 14603 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.70
Score	0%	54%

Review

Depending on where you apply effort and resistance, the wheel and axle can multiply:

45% Answer Correctly

	speed or power
	force or speed
	power or distance
	force or distance

Solution

If you apply the resistance to the axle and the effort to the wheel, the wheel and axle will multiply force and if you apply the resistance to the wheel and the effort to the axle, it will multiply speed.

Force of friction due to kinetic friction is __________ the force of friction due to static friction.

40% Answer Correctly

	lower than
	opposite
	higher than
	the same as

Solution

The formula for force of friction (F_f) is the same whether kinetic or static friction applies: F_{f =}μF_N. To distinguish between kinetic and static friction, μ_k and μ_s are often used in place of μ.

Lisa lifts a 25 pound box from the floor onto a loading dock 4 ft. off the ground. Sam slides the same box along a ramp to move it up another 4 ft. onto a flatbed truck. Who has done more work?

50% Answer Correctly

	They have done an equal amount of work
	Lisa
	Neither have done any work
	Sam

Solution

Work is force multiplied by distance. Because both Connie and Sam moved the same weight the same distance they have done an equal amount of work. Sam employed the mechnacial advantage of an inclined plane so he exerted less effort to do the work but the amount of work done was still the same.

What type of load is sudden and for a relatively short duration?

70% Answer Correctly

	concentrated load
	impact load
	dynamic load
	non-uniformly distributed load

Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.

5 What is the efficiency of a machine has work input of 145 ft⋅lb and work output of 72 ft⋅lb?

67% Answer Correctly

	50%
	2%
	25%
	100%

Solution

Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{72 ft⋅lb}{145 ft⋅lb} \times 100 \) \( = 50% \) %