ASVAB Mechanical Comprehension Practice Test 741912 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.67
Score	0%	73%

Review

1 What's the mechanical advantage of a wedge that's 3 inches wide and 15 inches long?

83% Answer Correctly

	5.5
	14
	6.5
	5

Solution

The mechanical advantage (MA) of a wedge is its length divided by its thickness:

MA = \( \frac{l}{t} \) = \( \frac{15 in.}{3 in.} \) = 5

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?

60% Answer Correctly

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

3 If the green box weighs 70 lbs. and is 7 ft. from the fulcrum, how far from the fulcrum would a 30 lbs. weight need to be placed to balance the lever?

61% Answer Correctly

	32.67 ft.
	16.33 ft.
	65.33 ft.
	0 ft.

Solution

To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

R_ad_a = R_bd_b

where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.

Solving for d_b, our missing value, and plugging in our variables yields:

d_b = \( \frac{R_ad_a}{R_b} \) = \( \frac{70 lbs. \times 7 ft.}{30 lbs.} \) = \( \frac{490 ft⋅lb}{30 lbs.} \) = 16.33 ft.

Collinear forces:

73% Answer Correctly

	act in a common plane
	are unrelated to each other
	act along the same line of action
	pass through a common point

Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

The steering wheel of a car is an example of which type of simple machine?

89% Answer Correctly

	fixed pulley
	block and tackle
	wheel and axle
	first-class lever

Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.