ASVAB Mechanical Comprehension Practice Test 249561 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.24
Score	0%	65%

Review

1 How much work can a 5 hp engine do in 5 seconds?

52% Answer Correctly

	1 ft⋅lb
	13750 ft⋅lb
	20 ft⋅lb
	10 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:
\( W = 5 hp \times 550 \frac{ft⋅lb}{s} \times 5s = 13750 ft⋅lb \)

2 What is the mechanical advantage of this inclined plane if the length of the ramp is 48 ft. and the height of the green box is 8 ft.?

82% Answer Correctly

	9
	12
	6
	7.5

Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In this case, the effort distance is the length of the ramp and the resistance distance is the height of the green box:

MA = \( \frac{d_e}{d_r} \) = \( \frac{48 ft.}{8 ft.} \) = 6

Which of the following is not a modulus of elasticity?

47% Answer Correctly

	stretch modulus
	shear modulus
	stress modulus
	bulk modulus

Solution

The modulus of elasticity measures how much a material or structure will deflect under stress. Stretch modulus is longitudinal stretch (like stretching raw bread dough), shear modulus is longitudinal deflection (like the horizontal displacement of a stack of magzines when a heavy object is placed upon them), and bulk modulus is compression of volume (like the compression of a loaf of bread under a heavy can at the bottom of a grocery bag).

A a seesaw / teeter-totter is an example of which of the following?

69% Answer Correctly

	inclined plane
	third-class lever
	second-class lever
	first-class lever

Solution

A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.

Hydraulics is the transmission of force through the use of which of the following?

73% Answer Correctly

	torque
	liquids
	air pressure
	gear systems

Solution

Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).