ASVAB Mechanical Comprehension Practice Test 502545 Results

Your Results Global Average
Questions 5 5
Correct 0 2.99
Score 0% 60%

Review

1 How much work can a 2 hp engine do in 7 seconds?
52% Answer Correctly
0 ft⋅lb
7700 ft⋅lb
4 ft⋅lb
1 ft⋅lb
Solution
Horsepower (hp) is a common measure of power output for complex machines. By definition, a 1 hp machine does 550 ft⋅lb of work in 1 second: 1 hp = 550 ft⋅lb/s. Substituting the variables for this problem gives us:
\( W = 2 hp \times 550 \frac{ft⋅lb}{s} \times 7s = 7700 ft⋅lb \)
2 If the handles of a wheelbarrow are 2.5 ft. from the wheel axle, how many pounds of force must you exert to lift the handles if it's carrying a 210 lbs. load concentrated at a point 0.5 ft. from the axle?
52% Answer Correctly
105
42
1050
168
Solution
This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: Fede = Frdr. In this problem we're looking for effort force:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{210 \times 0.5}{2.5} \)
\( F_e = \frac{105.0}{2.5} \)
\( F_e = 42 \)
3

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

80% Answer Correctly

efficiency

power

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.

4

Which of the following is not a characteristic of a ceramic?

61% Answer Correctly

low density

high melting point

chemically stable

low corrosive action
Solution

Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.

5 A 390 lb. barrel is rolled up a 5 ft. ramp to a platform that's 4 ft. tall. What effort is required to move the barrel?
53% Answer Correctly
936 lbs.
313.5 lbs.
314 lbs.
312 lbs.
Solution

This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:

Fede = Frdr

Plugging in the variables from this problem yields:

Fe x 5 ft. = 390 lbs. x 4 ft.
Fe = \( \frac{1560 ft⋅lb}{5 ft.} \) = 312 lbs.