ASVAB Mechanical Comprehension Practice Test 986058 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.29
Score	0%	66%

Review

Which of these is the formula for kinetic energy?

67% Answer Correctly

	\(KE = {m \over v^2 }\)
	\(KE = {1 \over 2}mv^2\)
	\(KE = mgh\)
	\(KE = {1 \over 2}mh^2\)

Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.

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

80% Answer Correctly

	power
	work
	mechanical advantage
	efficiency

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.

3 A = 5 ft., the green box weighs 10 lbs., and the blue box weighs 15 lbs. What does distance B need to be for this lever to balance?

65% Answer Correctly

	75 ft.
	3.33 ft.
	3 ft.
	2 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:

10 lbs. x 5 ft. = 15 lbs. x d_B

d_B = \( \frac{10 \times 5 ft⋅lb}{15 lbs.} \) = \( \frac{50 ft⋅lb}{15 lbs.} \) = 3.33 ft.

Which class of lever offers no mechanical advantage?

45% Answer Correctly

	third
	none of these, all levers offer mechanical advantage
	second
	first

Solution

A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.

A watt is the unit for which of the following?

71% Answer Correctly

	mechanical advantage
	power
	energy
	work

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.