ASVAB Mechanical Comprehension Practice Test 18731 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.07
Score	0%	61%

Review

The measure of how much of the power put into a machine is turned into movement or force is called:

56% Answer Correctly

	efficiency
	mechanical advantage
	force multiplication
	power

Solution

The efficiency of a machine describes how much of the power put into the machine is turned into movement or force. A 100% efficient machine would turn all of the input power into output movement or force. However, no machine is 100% efficient due to friction, heat, wear and other imperfections that consume input power without delivering any output.

2 How much work can a 8 hp engine do in 3 seconds?

52% Answer Correctly

	13200 ft⋅lb
	16 ft⋅lb
	2 ft⋅lb
	4 ft⋅lb

Solution

Horsepower (hp) is a common measure of power output for complex machines. By definition, a 1 hp machine does 550 ft⋅lb of work in 1 second: 1 hp = 550 ft⋅lb/s. Substituting the variables for this problem gives us:
\( W = 8 hp \times 550 \frac{ft⋅lb}{s} \times 3s = 13200 ft⋅lb \)

What type of load doesn't create specific stress points or vary with time?

59% Answer Correctly

	non-uniformly distributed load
	static uniformly distributed load
	concentrated load
	impact 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.

Which of the following surfaces would have the highest coefficient of friction?

77% Answer Correctly

	concrete
	steel
	ice
	marble

Solution

Coefficient of friction (μ) represents how much two materials resist sliding across each other. Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.

Power is the rate at which:

62% Answer Correctly

	friction is overcome
	input force is transferred to output force
	potential energy is converted into kinetic energy
	work is done

Solution

Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.