ASVAB Mechanical Comprehension Practice Test 477830 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.94
Score	0%	59%

Review

1 How much work can a 4 hp engine do in 8 seconds?

52% Answer Correctly

	16 ft⋅lb
	1 ft⋅lb
	0 ft⋅lb
	17600 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:
\( W = 4 hp \times 550 \frac{ft⋅lb}{s} \times 8s = 17600 ft⋅lb \)

2 If the radius of the axle is 5 and the radius of the wheel is 6, what is the mechanical advantage of this wheel and axle configuration?

52% Answer Correctly

	1.2
	-1
	1
	5

Solution

The mechanical advantage of a wheel and axle is the input radius divided by the output radius:

MA = \( \frac{r_i}{r_o} \)

In this case, the input radius (where the effort force is being applied) is 6 and the output radius (where the resistance is being applied) is 5 for a mechanical advantage of \( \frac{6}{5} \) = 1.2

A fixed pulley is useful for which of the following?

53% Answer Correctly

	multiplying the input distance
	changing the direction of the input force
	changing the direction of the output force
	multiplying the input force

Solution

A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.

Friction between two or more solid objects that are not moving relative to each other is called:

74% Answer Correctly

	kinetic friction
	static friction
	dynamic friction
	gravitational friction

Solution

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.

What is work?

60% Answer Correctly

	The potential for exertion
	The movement of an object by a force
	Force per unit distance
	Force per unit time

Solution

Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done. By definition, work is the displacement of an object resulting from applied force.