ASVAB Mechanical Comprehension Practice Test 804567 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.92
Score	0%	58%

Review

1 If this lever is in equilibrium with an effort force of 11.25 ft. lb. at the blue arrow and a resistance force of 9 ft. lb. at the green box, what is its mechanical advantage?

48% Answer Correctly

	-4.2
	0.8
	1.6
	2.8

Solution

Mechanical advantage (MA) is the ratio by which effort force relates to resistance force. If both forces are known, calculating MA is simply a matter of dividing resistance force by effort force:

MA = \( \frac{F_r}{F_e} \) = \( \frac{9 ft.}{11.25 ft.} \) = 0.8

In this case, the mechanical advantage is less than one meaning that each unit of effort force results in just 0.8 units of resistance force. However, a third class lever like this isn't designed to multiply force like a first class lever. A third class lever is designed to multiply distance and speed at the resistance by sacrificing force at the resistance. Different lever styles have different purposes and multiply forces in different ways.

Drag is a type of:

82% Answer Correctly

	potential energy
	friction
	kinetic energy
	work

Solution

Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.

3 If the handles of a wheelbarrow are 0.5 ft. from the wheel axle and the load is concentrated at a point 1.5 ft. from the axle, how many pounds of load will a 240 lbs. force lift?

47% Answer Correctly

	120
	84
	88.7
	80

Solution

This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: F_ed_e = F_rd_r. In this problem we're looking for resistance force:
\( F_r = \frac{F_e d_e}{d_r} \)
\( F_r = \frac{240 \times 0.5}{1.5} \)
\( F_r = \frac{120.0}{1.5} \)
\( F_r = 80 \)

Specific gravity is a comparison of the density of an object with the density of:

57% Answer Correctly

	air
	carbon
	oil
	water

Solution

Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.

A wedge converts force applied to its blunt end into force __________ its inclined surface.

57% Answer Correctly

	perpendicular to
	along
	parallel to
	opposite to

Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.