ASVAB Mechanical Comprehension Practice Test 776333 Results

Your Results Global Average
Questions 5 5
Correct 0 3.26
Score 0% 65%

Review

1 If input effort is 100 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 6?
79% Answer Correctly
1200ft⋅lb
150ft⋅lb
600 ft⋅lb
0ft⋅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 6 will multiply an input effort of 100 ft⋅lb by 6 to produce an output effort of 600 ft⋅lb.
2 How much work can a 5 hp engine do in 4 seconds?
52% Answer Correctly
20 ft⋅lb
2 ft⋅lb
10 ft⋅lb
11000 ft⋅lb
Solution
Horsepower (hp) is a common measure of power output for complex machines. By definition, a 1 hp machine does 550 ft⋅lb of work in 1 second: 1 hp = 550 ft⋅lb/s. Substituting the variables for this problem gives us:
\( W = 5 hp \times 550 \frac{ft⋅lb}{s} \times 4s = 11000 ft⋅lb \)
3 If you lift a 19 lbs. rock 3 ft. from the ground, how much work have you done?
71% Answer Correctly
57 ft⋅lb
6 ft⋅lb
27 ft⋅lb
16 ft⋅lb
Solution
Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 19 \times 3 \)
\( W = 57 \)
4

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

70% Answer Correctly

first-class lever

second-class lever

third-class lever

inclined plane
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.

5

Torque involves a perpendicular force applied to a lever arm that moves around a center of rotation. Increasing the length of the lever arm will do which of the following?

55% Answer Correctly

decrease torque

increase applied force

increase torque

decrease applied force
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).