ASVAB Mechanical Comprehension Practice Test 869652 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.01
Score	0%	60%

Review

1 A = 9 ft., the green box weighs 40 lbs., and the blue box weighs 90 lbs. What does distance B need to be for this lever to balance?

65% Answer Correctly

	360 ft.
	4 ft.
	2 ft.
	16 ft.

Solution

In order for this lever to balance, the torque acting on side A must equal the torque acting on side B. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

f_Ad_A = f_Bd_B

For this problem, the equation becomes:

40 lbs. x 9 ft. = 90 lbs. x d_B

d_B = \( \frac{40 \times 9 ft⋅lb}{90 lbs.} \) = \( \frac{360 ft⋅lb}{90 lbs.} \) = 4 ft.

Which of the following statements about this pulley configuration is false?

48% Answer Correctly

	Changes the direction of and multiplies the effort force
	Only multiplies the effort force
	Mechanical advantage is the number of ropes that support the resistance
	This is a block and tackle pulley configuration

Solution

A block and tackle is a combination of one or more fixed pulleys and one or more movable pulleys where the fixed pulleys change the direction of the effort force and the movable pulleys multiply it. The mechanical advantage is equal to the number of times the effort force changes direction and can be increased by adding more pulley wheels to the system. An easy way to find the mechanical advantage of a block and tackle pulley system is to count the number of ropes that support the resistance.

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

61% Answer Correctly

	chemically stable
	low corrosive action
	low density
	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.

An object's resistance to changes in direction is known as:

82% Answer Correctly

	weight
	inertia
	kinetic energy
	mass

Solution

The more mass a substance has the more force is required to move it or to change its direction. This resistance to changes in direction is known as inertia.

5 If the radius of the axle is 7 and the radius of the wheel is 12, what is the mechanical advantage of this wheel and axle configuration?

36% Answer Correctly

	1
	7
	1
	12

Solution

The mechanical advantage of a wheel and axle lies in the difference in radius between the inner (axle) wheel and the outer wheel. But, this mechanical advantage is only realized when the input effort and load are applied to different wheels. Applying both input effort and load to the same wheel results in a mechanical advantage of 1.