ASVAB Mechanical Comprehension Practice Test 156008 Results

Your Results Global Average
Questions 5 5
Correct 0 3.30
Score 0% 66%

Review

1

Which of these is the formula for kinetic energy?

68% Answer Correctly

\(KE = {1 \over 2}mh^2\)

\(KE = {1 \over 2}mv^2\)

\(KE = {m \over v^2 }\)

\(KE = mgh\)


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.


2

The work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. This defines which of the following?

60% Answer Correctly

mechanical advantage

work-energy theorem

Pascal's law

conservation of mechanical energy


Solution

The work-energy theorem states that the work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. Simply put, work imparts kinetic energy to the matter upon which the work is being done.


3

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

82% Answer Correctly

mass

inertia

kinetic energy

weight


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.


4 A 490 lb. barrel is rolled up a 5 ft. ramp to a platform that's 5 ft. tall. What effort is required to move the barrel?
53% Answer Correctly
980 lbs.
482 lbs.
163.3 lbs.
490 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:

Fede = Frdr

Plugging in the variables from this problem yields:

Fe x 5 ft. = 490 lbs. x 5 ft.
Fe = \( \frac{2450 ft⋅lb}{5 ft.} \) = 490 lbs.


5

Which of the following is the formula for torque?

61% Answer Correctly

τ = rF

τ = r/F

τ = F/r2

τ = F/r


Solution

Torque measures force applied during rotation: τ = rF.  Torque (τ, the Greek letter tau) = the radius of the lever arm (r) multiplied by the force (F) applied. Radius is measured from the center of rotation or fulcrum to the point at which the perpendicular force is being applied. The resulting unit for torque is newton-meter (N-m) or foot-pound (ft-lb).