ASVAB Mechanical Comprehension Practice Test 67392 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.98
Score	0%	60%

Review

A truck is using a rope to pull a car. Tension in the rope is greatest in which of the following places?

50% Answer Correctly

	in the middle
	tension is equal in all parts of the rope
	near the car
	near the truck

Solution

Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.

2 What is the efficiency of a machine has work input of 135 ft⋅lb and work output of 114 ft⋅lb?

67% Answer Correctly

	340%
	85%
	42%
	0%

Solution

Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{114 ft⋅lb}{135 ft⋅lb} \times 100 \) \( = 85% \) %

Specific gravity is a comparison of the density of an object with the density of:

57% Answer Correctly

	carbon
	air
	oil
	water

Solution

Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.

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

	Lisa
	Sam
	They have done an equal amount of work
	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.

Friction between two or more solid objects that are not moving relative to each other is called:

73% Answer Correctly

	static friction
	kinetic friction
	gravitational friction
	dynamic friction

Solution

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.