ASVAB Mechanical Comprehension Practice Test 286032 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.66
Score	0%	53%

Review

Which of the following will increase the mechanical advantage of this inclined plane?

59% Answer Correctly

	lengthen the ramp
	shorten the ramp
	lower the force acting at the blue arrow
	increase the force acting at the blue arrow

Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.

Which of the following is the formula for hydraulic pressure?

58% Answer Correctly

	P = FA
	P = F/A²
	P = FA²
	P = F/A

Solution

Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).

Two or more pulleys used together are called:

71% Answer Correctly

	gears
	wheel and axle
	third-class lever
	block and tackle

Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.

The advantage of using a third-class lever is that it increases:

37% Answer Correctly

	the distance traveled by the load
	the mechanical advantage of the lever
	the speed of the load
	the force applied to the load

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.

5 What is the power output of a 5 hp engine that's 55% efficient?

40% Answer Correctly

	6050 \( \frac{ft⋅lb}{s} \)
	1512.5 \( \frac{ft⋅lb}{s} \)
	3025 \( \frac{ft⋅lb}{s} \)
	756.3 \( \frac{ft⋅lb}{s} \)

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 5 hp x 550 \( \frac{ft⋅lb}{s} \) = 2750 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{55 \times 2750 \frac{ft⋅lb}{s}}{100} \) \( = \frac{151250 \frac{ft⋅lb}{s}}{100} \) = 1512.5 \( \frac{ft⋅lb}{s} \)