ASVAB Mechanical Comprehension Practice Test 855059 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.94
Score	0%	59%

Review

1 If A = 5 ft. and the green box weighs 5 lbs. what is the torque acting on the A side of this lever?

75% Answer Correctly

	25 ft⋅lb
	8 ft⋅lb
	6 ft⋅lb
	1 ft⋅lb

Solution

For a lever, torque is weight x distance from the fulcrum which, in this case, is: 5 ft. x 5 lbs. = 25 ft⋅lb

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

61% Answer Correctly

	low corrosive action
	low density
	chemically stable
	high melting point

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.

3 A 250 lb. barrel is rolled up a 16 ft. ramp to a platform that's 5 ft. tall. What effort is required to move the barrel?

53% Answer Correctly

	39.1 lbs.
	78.1 lbs.
	26 lbs.
	80.1 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:

F_ed_e = F_rd_r

Plugging in the variables from this problem yields:

F_e x 16 ft. = 250 lbs. x 5 ft.
F_e = \( \frac{1250 ft⋅lb}{16 ft.} \) = 78.1 lbs.

4 What is the power output of a 1 hp engine that's 65% efficient?

40% Answer Correctly

	89.4 \( \frac{ft⋅lb}{s} \)
	1430 \( \frac{ft⋅lb}{s} \)
	0 \( \frac{ft⋅lb}{s} \)
	357.5 \( \frac{ft⋅lb}{s} \)

Solution

\( Efficiency = \frac{Power_{out}}{Power_{in}} \times 100 \)
Solving for power out: \( P_{o} = \frac{E \times P_{i}}{100} \)
Knowing that 1 hp = 550 \( \frac{ft⋅lb}{s} \), P_i becomes 1 hp x 550 \( \frac{ft⋅lb}{s} \) = 550 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{65 \times 550 \frac{ft⋅lb}{s}}{100} \) \( = \frac{35750 \frac{ft⋅lb}{s}}{100} \) = 357.5 \( \frac{ft⋅lb}{s} \)

What is the first step to solving a problem where multiple forces are acting on an object?

61% Answer Correctly

	calculate the net force
	calculate potential energy
	calculate the total force
	calculate kinetic energy

Solution

In mechanics, multiple forces are often acting on a particular object and, taken together, produce the net force acting on that object. Like force, net force is a vector quantity in that it has magnitude and direction.