ASVAB Mechanical Comprehension Practice Test 901976 Results

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

Review

1 If the green arrow in this diagram represents 340 ft⋅lb of work, how far will the box move if it weighs 170 pounds?

72% Answer Correctly

	2 ft.
	1 ft.
	4 ft.
	340 ft.

Solution

The Law of Work states that the work put into a machine is equal to the work received from the machine under ideal conditions. In equation form, that's:

W_in = W_out
F_effort x d_effort = F_resistance x d_resistance

In this problem, the effort work is 340 ft⋅lb and the resistance force is 170 lbs. and we need to calculate the resistance distance:

W_in = F_resistance x d_resistance
340 ft⋅lb = 170 lbs. x d_resistance
d_resistance = \( \frac{340ft⋅lb}{170 lbs.} \) = 2 ft.

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?

36% Answer Correctly

	1
	0
	1
	-1

Solution

The mechanical advantage of a wheel and axle lies in the difference in radius between the inner (axle) wheel and the outer wheel. But, this mechanical advantage is only realized when the input effort and load are applied to different wheels. Applying both input effort and load to the same wheel results in a mechanical advantage of 1.

3 If the radius of the axle is 3 and the radius of the wheel is 6, what is the mechanical advantage of this wheel and axle configuration?

41% Answer Correctly

	-3
	3
	0.5
	6

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 3 and the output radius (where the resistance is being applied) is 6 for a mechanical advantage of \( \frac{3}{6} \) = 0.5

A fixed pulley has a mechanical advantage of:

68% Answer Correctly

	1
	-1
	2
	0

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.

One Horsepower (hp) is equal to how many watts?

76% Answer Correctly

	1
	746
	9.8
	1492

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.