ASVAB Mechanical Comprehension Practice Test 293889 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.45
Score	0%	69%

Review

The steering wheel of a car is an example of which type of simple machine?

89% Answer Correctly

	wheel and axle
	block and tackle
	fixed pulley
	first-class lever

Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.

Which of these is the formula for kinetic energy?

68% Answer Correctly

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

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.

3 If you lift a 10 lbs. rock 31 ft. from the ground, how much work have you done?

71% Answer Correctly

	155 ft⋅lb
	620 ft⋅lb
	0 ft⋅lb
	310 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 10 \times 31 \)
\( W = 310 \)

The principle of conservation of mechanical energy states that, as long as no other forces are applied, what will remain constant as an object falls?

45% Answer Correctly

	acceleration
	potential energy
	kinetic energy
	total mechanical energy

Solution

As an object falls, its potential energy is converted into kinetic energy. The principle of conservation of mechanical energy states that, as long as no other forces are applied, total mechanical energy (PE + KE) of the object will remain constant at all points in its descent.

The mechanical advantage of connected gears is proportional to which characteristic of the gears?

73% Answer Correctly

	speed
	circumference
	diameter
	number of teeth

Solution

The mechanical advantage (amount of change in speed or torque) of connected gears is proportional to the number of teeth each gear has. Called gear ratio, it's the ratio of the number of teeth on the larger gear to the number of teeth on the smaller gear. For example, a gear with 12 teeth connected to a gear with 9 teeth would have a gear ratio of 4:3.