ASVAB Mechanical Comprehension Practice Test 998229 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.11
Score	0%	62%

Review

The standard unit of energy is the:

73% Answer Correctly

	Watt
	Horsepower
	Volt
	Joule

Solution

The Joule (J) is the standard unit of energy and has the unit \({kg \times m^2} \over s^2\).

Which of the following surfaces would have the highest coefficient of friction?

77% Answer Correctly

	ice
	marble
	concrete
	steel

Solution

Coefficient of friction (μ) represents how much two materials resist sliding across each other. Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.

3 If the radius of the axle is 5 and the radius of the wheel is 8, what is the mechanical advantage of this wheel and axle configuration?

52% Answer Correctly

	1.6
	3
	5
	-3

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 8 and the output radius (where the resistance is being applied) is 5 for a mechanical advantage of \( \frac{8}{5} \) = 1.6

4 If A = 10 ft., B = 2 ft., C = 7 ft., the green box weighs 25 lbs. and the blue box weighs 35 lbs., what does the orange box have to weigh for this lever to balance?

44% Answer Correctly

	0 lbs.
	50 lbs.
	25.71 lbs.
	51.43 lbs.

Solution

In order for this lever to balance, the torque acting on each side of the fulrum must be equal. So, the torque produced by A must equal the torque produced by B and C. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

f_Ad_A = f_Bd_B + f_Cd_C

For this problem, this equation becomes:

25 lbs. x 10 ft. = 35 lbs. x 2 ft. + f_C x 7 ft.

250 ft. lbs. = 70 ft. lbs. + f_C x 7 ft.

f_C = \( \frac{250 ft. lbs. - 70 ft. lbs.}{7 ft.} \) = \( \frac{180 ft. lbs.}{7 ft.} \) = 25.71 lbs.

Normal force is generally equal to the __________ of an object.

61% Answer Correctly

	coefficient of friction
	density
	weight
	mass

Solution

Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.