ASVAB Mechanical Comprehension Practice Test 136439 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.51
Score	0%	50%

Review

1 How much work can a 5 hp engine do in 10 seconds?

52% Answer Correctly

	20 ft⋅lb
	1 ft⋅lb
	0 ft⋅lb
	27500 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:
\( W = 5 hp \times 550 \frac{ft⋅lb}{s} \times 10s = 27500 ft⋅lb \)

What is work?

60% Answer Correctly

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

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.

A fixed pulley is useful for which of the following?

53% Answer Correctly

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

Which class of lever offers no mechanical advantage?

45% Answer Correctly

	first
	none of these, all levers offer mechanical advantage
	second
	third

Solution

A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.

Force of friction due to kinetic friction is __________ the force of friction due to static friction.

40% Answer Correctly

	lower than
	higher than
	the same as
	opposite

Solution

The formula for force of friction (F_f) is the same whether kinetic or static friction applies: F_{f =}μF_N. To distinguish between kinetic and static friction, μ_k and μ_s are often used in place of μ.