ASVAB Mechanical Comprehension Practice Test 110483 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.06
Score	0%	61%

Review

The work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. This defines which of the following?

61% Answer Correctly

	Pascal's law
	conservation of mechanical energy
	work-energy theorem
	mechanical advantage

Solution

The work-energy theorem states that the work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. Simply put, work imparts kinetic energy to the matter upon which the work is being done.

One Horsepower (hp) is equal to how many watts?

76% Answer Correctly

	1492
	9.8
	1
	746

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.

Two or more pulleys used together are called:

71% Answer Correctly

	block and tackle
	gears
	wheel and axle
	third-class lever

Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.

4 How much work can a 4 hp engine do in 10 seconds?

53% Answer Correctly

	0 ft⋅lb
	8 ft⋅lb
	2 ft⋅lb
	22000 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:
\( W = 4 hp \times 550 \frac{ft⋅lb}{s} \times 10s = 22000 ft⋅lb \)

Which class of lever offers no mechanical advantage?

45% Answer Correctly

	second
	none of these, all levers offer mechanical advantage
	third
	first

Solution

A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.