ASVAB Mechanical Comprehension Practice Test 623054 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.02
Score	0%	60%

Review

The science that deals with motion and the forces that produce motion is called which of the following?

57% Answer Correctly

	mechanics
	engineering
	physics
	aeronautics

Solution

Mechanics deals with motion and the forces that produce motion.

What's the first gear in a gear train called?

57% Answer Correctly

	driven gear
	input gear
	driver gear
	idler gear

Solution

A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.

3 If input effort is 400 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 9?

79% Answer Correctly

	1800ft⋅lb
	0ft⋅lb
	3600 ft⋅lb
	44ft⋅lb

Solution

Mechanical advantage is the ratio of output force to input force and tells us by how many times a machine multiplies input effort. So, a machine with a mechanical advantage of 9 will multiply an input effort of 400 ft⋅lb by 9 to produce an output effort of 3600 ft⋅lb.

4 If the force applied at the blue arrow over 8 ft. moves the green box 1.33 ft., what is the mechanical advantage of this lever?

55% Answer Correctly

	3
	18
	6
	2

Solution

Mechanical advantage (MA) can be calculated knowing only the distance the effort (blue arrow) moves and the distance the resistance (green box) moves. The equation is:

MA = \( \frac{E_d}{R_d} \)

where E_d is the effort distance and R_d is the resistance distance. For this problem, the equation becomes:

MA = \( \frac{8 ft.}{1.33 ft.} \) = 6

You might be wondering how having an effort distance of 6 times the resistance distance is an advantage. Remember the principle of moments. For a lever in equilibrium the effort torque equals the resistance torque. Because torque is force x distance, if the effort distance is 6 times the resistance distance, the effort force must be \( \frac{1}{6} \) the resistance force. You're trading moving 6 times the distance for only having to use \( \frac{1}{6} \) the force.

Boyle's law defines the relationship between pressure and volume as:

57% Answer Correctly

	\(\frac{P_1}{P_2} = \frac{V_1}{V_2}\)
	\({P_1}{P_2} = {V_1}{V_2}\)
	\(\frac{P_1}{P_2} = \frac{V_2}{V_1}\)
	\(\frac{P_1}{P_2} = {V_1}{V_2}\)

Solution

Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional". Expressed as a formula, that's \(\frac{P_1}{P_2} = \frac{V_2}{V_1}\)