ASVAB Mechanical Comprehension Practice Test 783916 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.02
Score	0%	60%

Review

Coplanar forces:

62% Answer Correctly

	pass through a common point
	have opposite dimensions
	act in a common plane
	act along the same line of action

Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

A fixed pulley has a mechanical advantage of:

68% Answer Correctly

	-1
	1
	0
	2

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.

According to Boyle's law, for a fixed amount of gas kept at a fixed temperature, which of the following are inversely proportional?

63% Answer Correctly

	pressure, density
	pressure, volume
	density, volume
	volume, mass

Solution

Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional".

Which of these will have the most impact on the kinetic energy of an object?

54% Answer Correctly

	its direction
	its speed
	its mass
	its weight

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.

5 The radius of the axle is 7, the radius of the wheel is 8, and the blue box weighs 100 lbs. What is the effort force necessary to balance the load?

53% Answer Correctly

	56 lbs.
	9.12 lbs.
	87.72 lbs.
	8 lbs.

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 7 for a mechanical advantage of \( \frac{8}{7} \) = 1.14

MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{100 lbs.}{1.14} \) = 87.72 lbs.