ASVAB Mechanical Comprehension Practice Test 421960 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.35
Score	0%	67%

Review

1 A 290 lb. barrel is rolled up a 14 ft. ramp to a platform that's 1 ft. tall. What effort is required to move the barrel?

53% Answer Correctly

	20.7 lbs.
	22.8 lbs.
	62.1 lbs.
	41.4 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 14 ft. = 290 lbs. x 1 ft.
F_e = \( \frac{290 ft⋅lb}{14 ft.} \) = 20.7 lbs.

Power is the rate at which:

62% Answer Correctly

	potential energy is converted into kinetic energy
	input force is transferred to output force
	work is done
	friction is overcome

Solution

Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.

For any given surface, the coefficient of static friction is ___________ the coefficient of kinetic friction.

54% Answer Correctly

	opposite
	higher than
	lower than
	equal to

Solution

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).

4 If input effort is 700 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 9?

79% Answer Correctly

	6300 ft⋅lb
	1575ft⋅lb
	3150ft⋅lb
	25200ft⋅lb

Solution

Mechanical advantage is the ratio of output force to input force and tells us by how many times a machine multiplies input effort. So, a machine with a mechanical advantage of 9 will multiply an input effort of 700 ft⋅lb by 9 to produce an output effort of 6300 ft⋅lb.

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

82% Answer Correctly

	kinetic energy
	weight
	inertia
	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.