ASVAB Mechanical Comprehension Practice Test 502425 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.07
Score	0%	61%

Review

What is work?

60% Answer Correctly

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

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.

What type of load varies with time or affects a structure that experiences a high degree of movement?

66% Answer Correctly

	concentrated load
	static load
	dynamic load
	impact load

Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.

Depending on where you apply effort and resistance, the wheel and axle can multiply:

45% Answer Correctly

	power or distance
	force or speed
	force or distance
	speed or power

Solution

If you apply the resistance to the axle and the effort to the wheel, the wheel and axle will multiply force and if you apply the resistance to the wheel and the effort to the axle, it will multiply speed.

The force amplification achieved by using a tool, mechanical device or machine system is called:

80% Answer Correctly

	efficiency
	mechanical advantage
	power
	work

Solution

Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Such a device utilizes input force and trades off forces against movement to amplify and/or change its direction.

5 If the force applied at the blue arrow over 5 ft. moves the green box 0.56 ft., what is the mechanical advantage of this lever?

55% Answer Correctly

	8.1
	9
	9.9
	4

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 = \( \frac{5 ft.}{0.56 ft.} \) = 9

You might be wondering how having an effort distance of 9 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 9 times the resistance distance, the effort force must be \( \frac{1}{9} \) the resistance force. You're trading moving 9 times the distance for only having to use \( \frac{1}{9} \) the force.