ASVAB Mechanical Comprehension Practice Test 710263 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.93
Score	0%	59%

Review

1 What is the power output of a 4 hp engine that's 65% efficient?

40% Answer Correctly

	0 \( \frac{ft⋅lb}{s} \)
	1430 \( \frac{ft⋅lb}{s} \)
	4290 \( \frac{ft⋅lb}{s} \)
	5720 \( \frac{ft⋅lb}{s} \)

Solution

\( Efficiency = \frac{Power_{out}}{Power_{in}} \times 100 \)
Solving for power out: \( P_{o} = \frac{E \times P_{i}}{100} \)
Knowing that 1 hp = 550 \( \frac{ft⋅lb}{s} \), P_i becomes 4 hp x 550 \( \frac{ft⋅lb}{s} \) = 2200 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{65 \times 2200 \frac{ft⋅lb}{s}}{100} \) \( = \frac{143000 \frac{ft⋅lb}{s}}{100} \) = 1430 \( \frac{ft⋅lb}{s} \)

The mechanical advantage of a third class lever is always:

37% Answer Correctly

	less than one
	greater than one
	equal to one
	not equal to one

Solution

A third class lever is designed to multiply distance and speed at the expense of effort force. Because the effort force is greater than the resistance, the mechanical advantage of a third class lever is always less than one.

An example of a third class lever is a broom. The fulcrum is at your hand on the end of the broom, the effort force is your other hand in the middle, and the resistance is at the bottom bristles. The effort force of your hand in the middle multiplies the distance and speed of the bristles at the bottom but at the expense of producing a brushing force that's less than the force you're applying with your hand.

Power is the rate at which:

63% Answer Correctly

	friction is overcome
	work is done
	input force is transferred to output force
	potential energy is converted into kinetic energy

Solution

Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.

When all forces acting on a system cancel each other out, this is called:

81% Answer Correctly

	equilibrium
	potential energy
	rest
	stasis

Solution

When a system is stable or balanced (equilibrium) all forces acting on the system cancel each other out. In the case of torque, equilibrium means that the sum of the anticlockwise moments about a center of rotation equal the sum of the clockwise moments.

What type of load is sudden and for a relatively short duration?

70% Answer Correctly

	impact load
	concentrated load
	dynamic load
	non-uniformly distributed 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.