ASVAB Mechanical Comprehension Practice Test 373554 Results

Your Results Global Average
Questions 5 5
Correct 0 2.83
Score 0% 57%

Review

1

A wedge is most similar to what other type of simple machine?

70% Answer Correctly

second-class lever

inclined plane

first-class lever

third-class lever
Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.

2

Force of friction due to kinetic friction is __________ the force of friction due to static friction.

40% Answer Correctly

lower than

the same as

higher than

opposite
Solution

The formula for force of friction (Ff) is the same whether kinetic or static friction applies: Ff = μFN. To distinguish between kinetic and static friction, μk and μs are often used in place of μ.

3 If the handles of a wheelbarrow are 2.0 ft. from the wheel axle and the load is concentrated at a point 1.0 ft. from the axle, how many pounds of load will a 110 lbs. force lift?
47% Answer Correctly
304.7
110
0
220
Solution
This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: Fede = Frdr. In this problem we're looking for resistance force:
\( F_r = \frac{F_e d_e}{d_r} \)
\( F_r = \frac{110 \times 2.0}{1.0} \)
\( F_r = \frac{220.0}{1.0} \)
\( F_r = 220 \)
4 What is the efficiency of a machine has work input of 190 ft⋅lb and work output of 133 ft⋅lb?
67% Answer Correctly
0%
30%
17%
70%
Solution
Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{133 ft⋅lb}{190 ft⋅lb} \times 100 \) \( = 70% \) %
5

What is work?

60% Answer Correctly

Force per unit distance

The movement of an object by a force

The potential for exertion

Force per unit time
Solution

Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done. By definition, work is the displacement of an object resulting from applied force.