ASVAB Mechanical Comprehension Practice Test 902042 Results

Your Results Global Average
Questions 5 5
Correct 0 3.04
Score 0% 61%

Review

1

The science that deals with motion and the forces that produce motion is called which of the following?

57% Answer Correctly

engineering

aeronautics

mechanics

physics
Solution

Mechanics deals with motion and the forces that produce motion.

2 If a 25 lbs. weight is placed 7 ft. from the fulcrum at the blue arrow and the green box is 8 ft. from the fulcrum, how much would the green box have to weigh to balance the lever?
61% Answer Correctly
10.94 lbs.
65.63 lbs.
21.88 lbs.
43.75 lbs.
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:

Rada = Rbdb

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 Ra, our missing value, and plugging in our variables yields:

Ra = \( \frac{R_bd_b}{d_a} \) = \( \frac{25 lbs. \times 7 ft.}{8 ft.} \) = \( \frac{175 ft⋅lb}{8 ft.} \) = 21.88 lbs.

3 What is the efficiency of a machine has work input of 205 ft⋅lb and work output of 194 ft⋅lb?
67% Answer Correctly
1%
0%
95%
47%
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:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{194 ft⋅lb}{205 ft⋅lb} \times 100 \) \( = 95% \) %
4

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

57% Answer Correctly

oil

water

carbon

air
Solution

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

5

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".