ASVAB Mechanical Comprehension Practice Test 501 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.31
Score	0%	66%

Review

Which of these is the formula for kinetic energy?

67% Answer Correctly

	\(KE = {1 \over 2}mv^2\)
	\(KE = {1 \over 2}mh^2\)
	\(KE = {m \over v^2 }\)
	\(KE = mgh\)

Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.

2 If input effort is 600 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 7?

79% Answer Correctly

	4200 ft⋅lb
	16800ft⋅lb
	1050ft⋅lb
	2100ft⋅lb

Solution

Mechanical advantage is the ratio of output force to input force and tells us by how many times a machine multiplies input effort. So, a machine with a mechanical advantage of 7 will multiply an input effort of 600 ft⋅lb by 7 to produce an output effort of 4200 ft⋅lb.

Which of these is the formula for force?

76% Answer Correctly

	F = ma
	F = a/m
	F = m/a
	F = am²

Solution

Newton's Second Law of Motion states that "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object." This Law describes the linear relationship between mass and acceleration when it comes to force and leads to the formula F = ma or force equals mass multiplied by rate of acceleration.

4 If A = 11 ft., B = 3 ft., C = 9 ft., the green box weighs 45 lbs. and the blue box weighs 60 lbs., what does the orange box have to weigh for this lever to balance?

44% Answer Correctly

	135 lbs.
	35 lbs.
	70 lbs.
	17.5 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:

45 lbs. x 11 ft. = 60 lbs. x 3 ft. + f_C x 9 ft.

495 ft. lbs. = 180 ft. lbs. + f_C x 9 ft.

f_C = \( \frac{495 ft. lbs. - 180 ft. lbs.}{9 ft.} \) = \( \frac{315 ft. lbs.}{9 ft.} \) = 35 lbs.

What is the first step to solving a problem where multiple forces are acting on an object?

61% Answer Correctly

	calculate the net force
	calculate kinetic energy
	calculate the total force
	calculate potential energy

Solution

In mechanics, multiple forces are often acting on a particular object and, taken together, produce the net force acting on that object. Like force, net force is a vector quantity in that it has magnitude and direction.