ASVAB Mechanical Comprehension Practice Test 432334 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.03
Score	0%	61%

Review

The force amplification achieved by using a tool, mechanical device or machine system is called:

80% Answer Correctly

	power
	efficiency
	mechanical advantage
	work

Solution

Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Such a device utilizes input force and trades off forces against movement to amplify and/or change its direction.

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

59% Answer Correctly

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

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.

Lisa lifts a 25 pound box from the floor onto a loading dock 4 ft. off the ground. Sam slides the same box along a ramp to move it up another 4 ft. onto a flatbed truck. Who has done more work?

50% Answer Correctly

	They have done an equal amount of work
	Sam
	Lisa
	Neither have done any work

Solution

Work is force multiplied by distance. Because both Connie and Sam moved the same weight the same distance they have done an equal amount of work. Sam employed the mechnacial advantage of an inclined plane so he exerted less effort to do the work but the amount of work done was still the same.

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

54% Answer Correctly

	its speed
	its weight
	its direction
	its mass

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 If the green box weighs 35 lbs. and is 9 ft. from the fulcrum, how far from the fulcrum would a 65 lbs. weight need to be placed to balance the lever?

61% Answer Correctly

	2.42 ft.
	9.69 ft.
	14.54 ft.
	4.85 ft.

Solution

To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

R_ad_a = R_bd_b

where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.

Solving for d_b, our missing value, and plugging in our variables yields:

d_b = \( \frac{R_ad_a}{R_b} \) = \( \frac{35 lbs. \times 9 ft.}{65 lbs.} \) = \( \frac{315 ft⋅lb}{65 lbs.} \) = 4.85 ft.